CI: debug flaky webapp build
CI: debug flaky webapp build

### What is this PR for?
Debug flaky webapp builds

### What type of PR is it?
Improvement

### What is the Jira issue?
[ZEPPELIN-836](https://issues.apache.org/jira/browse/ZEPPELIN-836)

### How should this be tested?
CI must be green and include Travis exit code in case of success and `npm_debug.log` in case of failure

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

Author: Alexander Bezzubov <bzz@apache.org>

Closes #871 from bzz/debug-flaky-webapp-ci and squashes the following commits:

336fe96 [Alexander Bezzubov] CI: update logs \w debug info on webapp build and Travis exit code

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