Improve README.md
Improve README.md

### What is this PR for?

Update README.md

- Unify code block styles (fenced code blocks).
- Add syntax highlighting in some code blocks.
- Fix unwanted link in option: `-Pmapr[version]`.
- General formatting.

### What type of PR is it?
Documentation

### Todos
None.

### What is the Jira issue?
N/A

### How should this be tested?
Preview the rendered README.md on GitHub.
View `README.md` on [cyhsutw/incubator-zeppelin:better-readme](https://github.com/cyhsutw/incubator-zeppelin/tree/better-readme)

### Screenshots (if appropriate)

Unwanted link in option: `-Pmapr[version]`:
![screen shot 2016-04-16 at 12 21 34 am](https://cloud.githubusercontent.com/assets/1046917/14578386/6405700e-03b9-11e6-98f8-135d8dbc9598.png)

### Questions:
* Does the licenses files need update? *no*
* Is there breaking changes for older versions? *no*
* Does this needs documentation? *no*

Author: Cheng-Yu Hsu <m@cyhsu.me>

Closes #839 from cyhsutw/better-readme and squashes the following commits:

93f5c87 [Cheng-Yu Hsu] cleanup whitespace
ff8f7f2 [Cheng-Yu Hsu] clarity the description of `-Pr` and `-Psparkr`
facdf66 [Cheng-Yu Hsu] add `-Pr` and `-Psparkr`
127955b [Cheng-Yu Hsu] update README.md : add `-Psparkr` option
aee2f43 [Cheng-Yu Hsu] Update README.md

wary/zeppelin,astroshim/zeppelin,sohaibiftikhar/zeppelin,Madhuka/incubator-zeppelin,sravan-s/zeppelin,wary/zeppelin,AlexanderShoshin/zeppelin,brigade/incubator-zeppelin,hammertank/zeppelin,zjffdu/zeppelin,r-kamath/incubator-zeppelin,AlexanderShoshin/zeppelin,zetaris/zeppelin,SachinJanani/zeppelin,prabhjyotsingh/zeppelin,apache/zeppelin,sohaibiftikhar/zeppelin,tinkoff-dwh/zeppelin,sergeymazin/zeppelin,anthonycorbacho/incubator-zeppelin,Altiscale/incubator-zeppelin,fogbeam/zeppelin_mirror,IceKhan13/zeppelin,raysteam/zeppelin,sagarkulkarni3592/incubator-zeppelin,chilang/zeppelin,datalayer/zeppelin-datalayer,sagarkulkarni3592/incubator-zeppelin,ravicodder/incubator-zeppelin,Solution-Global/zeppelin,Madhuka/incubator-zeppelin,hkropp/incubator-zeppelin,AlexanderShoshin/zeppelin,tinkoff-dwh/zeppelin,r-kamath/incubator-zeppelin,jongyoul/zeppelin,digitalreasoning/incubator-zeppelin,cfries/zeppelin,vrlo/zeppelin,Leemoonsoo/incubator-zeppelin,vipul1409/zeppelin,lresende/incubator-zeppelin,optimizely/incubator-zeppelin,astroshim/incubator-zeppelin,rlugojr/incubator-zeppelin,jlagarden/zeppelin,herval/zeppelin,minahlee/zeppelin,namanmishra91/zeppelin,fogbeam/zeppelin_mirror,yorek/zeppelin,onkarshedge/incubator-zeppelin,brigade/incubator-zeppelin,Nova-Boy/zeppelin,mwkang/zeppelin,nikste/incubator-zeppelin,lobamba/zeppelin,1ambda/zeppelin,sergeymazin/zeppelin,r-kamath/zeppelin,r-kamath/incubator-zeppelin,wary/zeppelin,1ambda/zeppelin,sravan-s/zeppelin,tzolov/incubator-zeppelin,wary/zeppelin,soralee/zeppelin,Madhuka/incubator-zeppelin,cfries/zeppelin,optimizely/incubator-zeppelin,Leemoonsoo/zeppelin,jongyoul/zeppelin,Madhuka/incubator-zeppelin,namanmishra91/zeppelin,minahlee/incubator-zeppelin,prabhjyotsingh/incubator-zeppelin,karuppayya/zeppelin,yu74n/zeppelin,minahlee/zeppelin,SarunasG/zeppelin-oidc,yu74n/zeppelin,1ambda/zeppelin,mwkang/zeppelin,AlexanderShoshin/zeppelin,spacewalkman/incubator-zeppelin,SarunasG/zeppelin-oidc,ravicodder/incubator-zeppelin,lresende/incubator-zeppelin,sagarkulkarni3592/incubator-zeppelin,Leemoonsoo/incubator-zeppelin,fogbeam/zeppelin_mirror,SachinJanani/zeppelin,herval/zeppelin,jongyoul/zeppelin,benoyantony/zeppelin,tinkoff-dwh/zeppelin,Madhuka/incubator-zeppelin,1ambda/zeppelin,spacewalkman/incubator-zeppelin,hammertank/zeppelin,mwpenny/zeppelin-esri,SachinJanani/zeppelin,datalayer/zeppelin-datalayer,suvam97/zeppelin,jongyoul/incubator-zeppelin,sagarkulkarni3592/incubator-zeppelin,sctincman/zeppelin,volumeint/zeppelin,Leemoonsoo/incubator-zeppelin,tinkoff-dwh/zeppelin,herval/zeppelin,cfries/zeppelin,rlugojr/incubator-zeppelin,prabhjyotsingh/zeppelin,onkarshedge/incubator-zeppelin,zetaris/zeppelin,digitalreasoning/incubator-zeppelin,yorek/zeppelin,SachinJanani/zeppelin,tinkoff-dwh/zeppelin,radicalbit/incubator-zeppelin,lresende/incubator-zeppelin,optimizely/incubator-zeppelin,herval/zeppelin,hammertank/zeppelin,tillrohrmann/incubator-zeppelin,yorek/zeppelin,sctincman/zeppelin,joroKr21/incubator-zeppelin,suvam97/zeppelin,zjffdu/zeppelin,soralee/zeppelin,IceKhan13/zeppelin,radicalbit/incubator-zeppelin,openthings/zeppelin,soralee/zeppelin,zetaris/zeppelin,sergeymazin/zeppelin,chilang/zeppelin,VipinRathor/zeppelin,apache/zeppelin,prasadwagle/incubator-zeppelin,prasadwagle/incubator-zeppelin,soralee/zeppelin,vrlo/zeppelin,openthings/zeppelin,vgmartinez/incubator-zeppelin,hkropp/incubator-zeppelin,Solution-Global/zeppelin,sctincman/zeppelin,lresende/incubator-zeppelin,doanduyhai/incubator-zeppelin,YuanGunGun/zeppelin,doanduyhai/incubator-zeppelin,datalayer/zeppelin,minahlee/zeppelin,minahlee/zeppelin,prasadwagle/incubator-zeppelin,spacewalkman/incubator-zeppelin,Altiscale/incubator-zeppelin,volumeint/zeppelin,brigade/incubator-zeppelin,prasadwagle/incubator-zeppelin,rconline/zeppelin,spacewalkman/incubator-zeppelin,datalayer/zeppelin,digitalreasoning/incubator-zeppelin,brigade/incubator-zeppelin,datalayer/zeppelin,pravin-dsilva/zeppelin,Altiscale/incubator-zeppelin,cfries/zeppelin,ravicodder/incubator-zeppelin,astroshim/incubator-zeppelin,rlugojr/incubator-zeppelin,rconline/zeppelin,vrlo/zeppelin,IceKhan13/zeppelin,pellmont/zeppelin,zetaris/zeppelin,datalayer/zeppelin-datalayer,suvam97/zeppelin,onkarshedge/incubator-zeppelin,nikste/incubator-zeppelin,jongyoul/incubator-zeppelin,mwkang/zeppelin,lobamba/zeppelin,tinkoff-dwh/zeppelin,herval/zeppelin,optimizely/incubator-zeppelin,mwkang/zeppelin,namanmishra91/zeppelin,onkarshedge/incubator-zeppelin,r-kamath/zeppelin,cquptEthan/incubator-zeppelin,openthings/zeppelin,anthonycorbacho/incubator-zeppelin,rerngvit/incubator-zeppelin,jlagarden/zeppelin,rerngvit/incubator-zeppelin,yorek/zeppelin,Leemoonsoo/zeppelin,prabhjyotsingh/incubator-zeppelin,namanmishra91/zeppelin,lobamba/zeppelin,cfries/zeppelin,lresende/incubator-zeppelin,chilang/zeppelin,radicalbit/incubator-zeppelin,karuppayya/zeppelin,jlagarden/zeppelin,mfelgamal/zeppelin,chilang/zeppelin,volumeint/zeppelin,r-kamath/zeppelin,fogbeam/zeppelin_mirror,zjffdu/zeppelin,cquptEthan/incubator-zeppelin,astroshim/zeppelin,jongyoul/zeppelin,vipul1409/zeppelin,astroshim/zeppelin,jlagarden/zeppelin,sagarkulkarni3592/incubator-zeppelin,Leemoonsoo/zeppelin,Leemoonsoo/zeppelin,jlagarden/zeppelin,cquptEthan/incubator-zeppelin,mwkang/zeppelin,mwpenny/zeppelin-esri,jlagarden/zeppelin,sravan-s/zeppelin,jongyoul/zeppelin,Nova-Boy/zeppelin,prasadwagle/incubator-zeppelin,anthonycorbacho/incubator-zeppelin,Leemoonsoo/zeppelin,mwkang/zeppelin,doanduyhai/incubator-zeppelin,AlexanderShoshin/zeppelin,prabhjyotsingh/incubator-zeppelin,lobamba/zeppelin,volumeint/zeppelin,pellmont/zeppelin,fogbeam/zeppelin_mirror,nikste/incubator-zeppelin,VipinRathor/zeppelin,chilang/zeppelin,apache/zeppelin,vipul1409/zeppelin,anthonycorbacho/incubator-zeppelin,raysteam/zeppelin,zetaris/zeppelin,AlexanderShoshin/zeppelin,rerngvit/incubator-zeppelin,astroshim/incubator-zeppelin,pravin-dsilva/zeppelin,optimizely/incubator-zeppelin,benoyantony/zeppelin,sohaibiftikhar/zeppelin,lresende/incubator-zeppelin,tzolov/incubator-zeppelin,sctincman/zeppelin,minahlee/zeppelin,soralee/zeppelin,nikste/incubator-zeppelin,astroshim/zeppelin,hammertank/zeppelin,sravan-s/zeppelin,karuppayya/zeppelin,pravin-dsilva/zeppelin,minahlee/zeppelin,digitalreasoning/incubator-zeppelin,tillrohrmann/incubator-zeppelin,astroshim/zeppelin,herval/zeppelin,minahlee/incubator-zeppelin,tinkoff-dwh/zeppelin,pellmont/zeppelin,joroKr21/incubator-zeppelin,datalayer/zeppelin,wary/zeppelin,astroshim/incubator-zeppelin,IceKhan13/zeppelin,Madhuka/incubator-zeppelin,jongyoul/incubator-zeppelin,vipul1409/zeppelin,pravin-dsilva/zeppelin,r-kamath/zeppelin,rlugojr/incubator-zeppelin,sagarkulkarni3592/incubator-zeppelin,sctincman/zeppelin,Altiscale/incubator-zeppelin,digitalreasoning/incubator-zeppelin,mfelgamal/zeppelin,rerngvit/incubator-zeppelin,VipinRathor/zeppelin,jongyoul/zeppelin,minahlee/incubator-zeppelin,VipinRathor/zeppelin,spacewalkman/incubator-zeppelin,VipinRathor/zeppelin,doanduyhai/incubator-zeppelin,sravan-s/zeppelin,apache/incubator-zeppelin,ravicodder/incubator-zeppelin,anthonycorbacho/incubator-zeppelin,Leemoonsoo/zeppelin,joroKr21/incubator-zeppelin,raysteam/zeppelin,chilang/zeppelin,rconline/zeppelin,radicalbit/incubator-zeppelin,YuanGunGun/zeppelin,SachinJanani/zeppelin,mfelgamal/zeppelin,sctincman/zeppelin,Nova-Boy/zeppelin,raysteam/zeppelin,Leemoonsoo/incubator-zeppelin,tillrohrmann/incubator-zeppelin,prabhjyotsingh/zeppelin,prasadwagle/incubator-zeppelin,Nova-Boy/zeppelin,brigade/incubator-zeppelin,minahlee/incubator-zeppelin,datalayer/zeppelin-datalayer,minahlee/incubator-zeppelin,mwpenny/zeppelin-esri,optimizely/incubator-zeppelin,apache/incubator-zeppelin,radicalbit/incubator-zeppelin,digitalreasoning/incubator-zeppelin,suvam97/zeppelin,Leemoonsoo/zeppelin,namanmishra91/zeppelin,SarunasG/zeppelin-oidc,rerngvit/incubator-zeppelin,yu74n/zeppelin,yorek/zeppelin,hkropp/incubator-zeppelin,Solution-Global/zeppelin,ravicodder/incubator-zeppelin,soralee/zeppelin,yu74n/zeppelin,vgmartinez/incubator-zeppelin,mfelgamal/zeppelin,optimizely/incubator-zeppelin,IceKhan13/zeppelin,benoyantony/zeppelin,anthonycorbacho/incubator-zeppelin,YuanGunGun/zeppelin,namanmishra91/zeppelin,cquptEthan/incubator-zeppelin,lresende/incubator-zeppelin,tzolov/incubator-zeppelin,tzolov/incubator-zeppelin,karuppayya/zeppelin,rlugojr/incubator-zeppelin,Solution-Global/zeppelin,openthings/zeppelin,r-kamath/incubator-zeppelin,pravin-dsilva/zeppelin,astroshim/incubator-zeppelin,spacewalkman/incubator-zeppelin,apache/zeppelin,joroKr21/incubator-zeppelin,prasadwagle/incubator-zeppelin,karuppayya/zeppelin,zjffdu/zeppelin,herval/zeppelin,vrlo/zeppelin,1ambda/zeppelin,radicalbit/incubator-zeppelin,pravin-dsilva/zeppelin,jongyoul/incubator-zeppelin,zetaris/zeppelin,rerngvit/incubator-zeppelin,IceKhan13/zeppelin,apache/zeppelin,pellmont/zeppelin,doanduyhai/incubator-zeppelin,1ambda/zeppelin,apache/incubator-zeppelin,vipul1409/zeppelin,openthings/zeppelin,sohaibiftikhar/zeppelin,ravicodder/incubator-zeppelin,hammertank/zeppelin,benoyantony/zeppelin,mwpenny/zeppelin-esri,tillrohrmann/incubator-zeppelin,tzolov/incubator-zeppelin,rconline/zeppelin,tillrohrmann/incubator-zeppelin,sagarkulkarni3592/incubator-zeppelin,mfelgamal/zeppelin,jongyoul/incubator-zeppelin,datalayer/zeppelin,prabhjyotsingh/incubator-zeppelin,cfries/zeppelin,rerngvit/incubator-zeppelin,sergeymazin/zeppelin,zjffdu/zeppelin,SachinJanani/zeppelin,openthings/zeppelin,mwpenny/zeppelin-esri,yorek/zeppelin,YuanGunGun/zeppelin,doanduyhai/incubator-zeppelin,mwkang/zeppelin,hammertank/zeppelin,tzolov/incubator-zeppelin,hkropp/incubator-zeppelin,namanmishra91/zeppelin,pellmont/zeppelin,brigade/incubator-zeppelin,sergeymazin/zeppelin,wary/zeppelin,raysteam/zeppelin,volumeint/zeppelin,joroKr21/incubator-zeppelin,digitalreasoning/incubator-zeppelin,sravan-s/zeppelin,apache/zeppelin,vrlo/zeppelin,fogbeam/zeppelin_mirror,pravin-dsilva/zeppelin,datalayer/zeppelin,cquptEthan/incubator-zeppelin,vipul1409/zeppelin,Nova-Boy/zeppelin,sctincman/zeppelin,tillrohrmann/incubator-zeppelin,YuanGunGun/zeppelin,hkropp/incubator-zeppelin,yu74n/zeppelin,mfelgamal/zeppelin,sohaibiftikhar/zeppelin,rconline/zeppelin,apache/incubator-zeppelin,openthings/zeppelin,Nova-Boy/zeppelin,zjffdu/zeppelin,r-kamath/zeppelin,rconline/zeppelin,prabhjyotsingh/zeppelin,onkarshedge/incubator-zeppelin,benoyantony/zeppelin,joroKr21/incubator-zeppelin,rlugojr/incubator-zeppelin,Altiscale/incubator-zeppelin,jongyoul/incubator-zeppelin,raysteam/zeppelin,zjffdu/zeppelin,astroshim/incubator-zeppelin,cquptEthan/incubator-zeppelin,Altiscale/incubator-zeppelin,jlagarden/zeppelin,sravan-s/zeppelin,onkarshedge/incubator-zeppelin,apache/incubator-zeppelin,hkropp/incubator-zeppelin,datalayer/zeppelin,volumeint/zeppelin,cfries/zeppelin,SarunasG/zeppelin-oidc,spacewalkman/incubator-zeppelin,rconline/zeppelin,Solution-Global/zeppelin,brigade/incubator-zeppelin,vgmartinez/incubator-zeppelin,lobamba/zeppelin,suvam97/zeppelin,astroshim/zeppelin,apache/incubator-zeppelin,hammertank/zeppelin,lobamba/zeppelin,nikste/incubator-zeppelin,joroKr21/incubator-zeppelin,r-kamath/incubator-zeppelin,minahlee/zeppelin,radicalbit/incubator-zeppelin,tillrohrmann/incubator-zeppelin,Nova-Boy/zeppelin,prabhjyotsingh/zeppelin,SachinJanani/zeppelin,yu74n/zeppelin,chilang/zeppelin,prabhjyotsingh/zeppelin,Leemoonsoo/zeppelin,vrlo/zeppelin,doanduyhai/incubator-zeppelin,IceKhan13/zeppelin,benoyantony/zeppelin,onkarshedge/incubator-zeppelin,AlexanderShoshin/zeppelin,anthonycorbacho/incubator-zeppelin,lobamba/zeppelin,prabhjyotsingh/incubator-zeppelin,SarunasG/zeppelin-oidc,sergeymazin/zeppelin,suvam97/zeppelin,pellmont/zeppelin,vipul1409/zeppelin,SarunasG/zeppelin-oidc,wary/zeppelin,mfelgamal/zeppelin,YuanGunGun/zeppelin,prabhjyotsingh/incubator-zeppelin,joroKr21/incubator-zeppelin,mwpenny/zeppelin-esri,yorek/zeppelin,sohaibiftikhar/zeppelin,Solution-Global/zeppelin,fogbeam/zeppelin_mirror,astroshim/zeppelin,benoyantony/zeppelin,karuppayya/zeppelin,r-kamath/zeppelin,karuppayya/zeppelin,yu74n/zeppelin,nikste/incubator-zeppelin,VipinRathor/zeppelin,vgmartinez/incubator-zeppelin,suvam97/zeppelin,VipinRathor/zeppelin,Solution-Global/zeppelin,pellmont/zeppelin,r-kamath/incubator-zeppelin,ravicodder/incubator-zeppelin,Madhuka/incubator-zeppelin,prabhjyotsingh/zeppelin,r-kamath/zeppelin,jongyoul/zeppelin,cquptEthan/incubator-zeppelin,apache/zeppelin,Leemoonsoo/incubator-zeppelin,vrlo/zeppelin,volumeint/zeppelin,sergeymazin/zeppelin,SarunasG/zeppelin-oidc,vgmartinez/incubator-zeppelin,zetaris/zeppelin,1ambda/zeppelin,soralee/zeppelin,r-kamath/incubator-zeppelin,raysteam/zeppelin,vgmartinez/incubator-zeppelin,YuanGunGun/zeppelin,Leemoonsoo/incubator-zeppelin,sohaibiftikhar/zeppelin,mwpenny/zeppelin-esri