Add remaining codebases to README.md.
Add remaining codebases to README.md.

The README should link to all the Zulip codebases. Also, it makes
sense to split up app code from integration and other glue code.

Fixes: #674.

sup95/zulip,souravbadami/zulip,arpith/zulip,samatdav/zulip,paxapy/zulip,punchagan/zulip,krtkmj/zulip,isht3/zulip,sonali0901/zulip,Galexrt/zulip,mahim97/zulip,verma-varsha/zulip,jrowan/zulip,niftynei/zulip,AZtheAsian/zulip,Vallher/zulip,paxapy/zulip,andersk/zulip,Vallher/zulip,Diptanshu8/zulip,andersk/zulip,vikas-parashar/zulip,synicalsyntax/zulip,eeshangarg/zulip,jrowan/zulip,reyha/zulip,shubhamdhama/zulip,peguin40/zulip,SmartPeople/zulip,Juanvulcano/zulip,kou/zulip,dawran6/zulip,tommyip/zulip,TigorC/zulip,sharmaeklavya2/zulip,paxapy/zulip,dattatreya303/zulip,KingxBanana/zulip,peguin40/zulip,Galexrt/zulip,arpith/zulip,showell/zulip,Diptanshu8/zulip,ahmadassaf/zulip,susansls/zulip,Juanvulcano/zulip,zacps/zulip,peguin40/zulip,timabbott/zulip,souravbadami/zulip,krtkmj/zulip,grave-w-grave/zulip,brainwane/zulip,shubhamdhama/zulip,KingxBanana/zulip,Galexrt/zulip,christi3k/zulip,peiwei/zulip,rishig/zulip,mohsenSy/zulip,JPJPJPOPOP/zulip,sharmaeklavya2/zulip,peiwei/zulip,SmartPeople/zulip,peiwei/zulip,sharmaeklavya2/zulip,ahmadassaf/zulip,ahmadassaf/zulip,amyliu345/zulip,Vallher/zulip,shubhamdhama/zulip,AZtheAsian/zulip,AZtheAsian/zulip,cosmicAsymmetry/zulip,calvinleenyc/zulip,umkay/zulip,JPJPJPOPOP/zulip,Galexrt/zulip,sharmaeklavya2/zulip,christi3k/zulip,dawran6/zulip,vabs22/zulip,rishig/zulip,mahim97/zulip,Jianchun1/zulip,SmartPeople/zulip,samatdav/zulip,reyha/zulip,rishig/zulip,mohsenSy/zulip,mohsenSy/zulip,sup95/zulip,niftynei/zulip,krtkmj/zulip,ahmadassaf/zulip,sup95/zulip,amanharitsh123/zulip,Diptanshu8/zulip,KingxBanana/zulip,krtkmj/zulip,timabbott/zulip,j831/zulip,susansls/zulip,ryanbackman/zulip,christi3k/zulip,timabbott/zulip,aakash-cr7/zulip,souravbadami/zulip,brockwhittaker/zulip,shubhamdhama/zulip,jrowan/zulip,blaze225/zulip,hackerkid/zulip,TigorC/zulip,christi3k/zulip,andersk/zulip,sharmaeklavya2/zulip,brockwhittaker/zulip,zacps/zulip,JPJPJPOPOP/zulip,aakash-cr7/zulip,amanharitsh123/zulip,Jianchun1/zulip,rishig/zulip,jainayush975/zulip,punchagan/zulip,eeshangarg/zulip,j831/zulip,KingxBanana/zulip,dhcrzf/zulip,peiwei/zulip,synicalsyntax/zulip,sup95/zulip,aakash-cr7/zulip,aakash-cr7/zulip,Juanvulcano/zulip,vaidap/zulip,Diptanshu8/zulip,PhilSk/zulip,niftynei/zulip,kou/zulip,brainwane/zulip,dawran6/zulip,vabs22/zulip,amanharitsh123/zulip,joyhchen/zulip,jphilipsen05/zulip,susansls/zulip,umkay/zulip,brainwane/zulip,tommyip/zulip,rishig/zulip,dattatreya303/zulip,mahim97/zulip,umkay/zulip,rishig/zulip,hackerkid/zulip,umkay/zulip,sonali0901/zulip,vikas-parashar/zulip,ryanbackman/zulip,zulip/zulip,dhcrzf/zulip,Galexrt/zulip,brainwane/zulip,rht/zulip,cosmicAsymmetry/zulip,grave-w-grave/zulip,andersk/zulip,zacps/zulip,punchagan/zulip,ryanbackman/zulip,shubhamdhama/zulip,synicalsyntax/zulip,krtkmj/zulip,peiwei/zulip,umkay/zulip,jackrzhang/zulip,j831/zulip,j831/zulip,susansls/zulip,ahmadassaf/zulip,zacps/zulip,vabs22/zulip,andersk/zulip,cosmicAsymmetry/zulip,kou/zulip,rht/zulip,mohsenSy/zulip,samatdav/zulip,hackerkid/zulip,isht3/zulip,souravbadami/zulip,souravbadami/zulip,joyhchen/zulip,rht/zulip,TigorC/zulip,aakash-cr7/zulip,sup95/zulip,calvinleenyc/zulip,blaze225/zulip,hackerkid/zulip,zacps/zulip,PhilSk/zulip,verma-varsha/zulip,cosmicAsymmetry/zulip,jrowan/zulip,ryanbackman/zulip,tommyip/zulip,rht/zulip,jackrzhang/zulip,verma-varsha/zulip,jphilipsen05/zulip,sonali0901/zulip,paxapy/zulip,krtkmj/zulip,reyha/zulip,tommyip/zulip,jrowan/zulip,reyha/zulip,AZtheAsian/zulip,sonali0901/zulip,rishig/zulip,PhilSk/zulip,vaidap/zulip,zulip/zulip,Vallher/zulip,brainwane/zulip,cosmicAsymmetry/zulip,synicalsyntax/zulip,blaze225/zulip,brockwhittaker/zulip,Galexrt/zulip,ahmadassaf/zulip,aakash-cr7/zulip,eeshangarg/zulip,Galexrt/zulip,cosmicAsymmetry/zulip,shubhamdhama/zulip,timabbott/zulip,amyliu345/zulip,shubhamdhama/zulip,amyliu345/zulip,vaidap/zulip,tommyip/zulip,PhilSk/zulip,zulip/zulip,vaidap/zulip,JPJPJPOPOP/zulip,verma-varsha/zulip,reyha/zulip,mahim97/zulip,showell/zulip,hackerkid/zulip,vikas-parashar/zulip,eeshangarg/zulip,peguin40/zulip,mohsenSy/zulip,samatdav/zulip,ahmadassaf/zulip,christi3k/zulip,vikas-parashar/zulip,grave-w-grave/zulip,tommyip/zulip,amanharitsh123/zulip,tommyip/zulip,amyliu345/zulip,grave-w-grave/zulip,susansls/zulip,vabs22/zulip,vabs22/zulip,JPJPJPOPOP/zulip,grave-w-grave/zulip,sonali0901/zulip,joyhchen/zulip,joyhchen/zulip,dattatreya303/zulip,jainayush975/zulip,punchagan/zulip,peiwei/zulip,souravbadami/zulip,zacps/zulip,arpith/zulip,synicalsyntax/zulip,j831/zulip,dhcrzf/zulip,amanharitsh123/zulip,vikas-parashar/zulip,blaze225/zulip,jainayush975/zulip,samatdav/zulip,synicalsyntax/zulip,jphilipsen05/zulip,vaidap/zulip,susansls/zulip,verma-varsha/zulip,showell/zulip,blaze225/zulip,kou/zulip,Vallher/zulip,zulip/zulip,timabbott/zulip,umkay/zulip,mahim97/zulip,rht/zulip,paxapy/zulip,reyha/zulip,Jianchun1/zulip,niftynei/zulip,rht/zulip,mohsenSy/zulip,peguin40/zulip,dawran6/zulip,jackrzhang/zulip,isht3/zulip,Vallher/zulip,Juanvulcano/zulip,amyliu345/zulip,calvinleenyc/zulip,eeshangarg/zulip,blaze225/zulip,mahim97/zulip,brockwhittaker/zulip,synicalsyntax/zulip,SmartPeople/zulip,ryanbackman/zulip,verma-varsha/zulip,brockwhittaker/zulip,jrowan/zulip,vabs22/zulip,punchagan/zulip,vikas-parashar/zulip,arpith/zulip,peguin40/zulip,calvinleenyc/zulip,amanharitsh123/zulip,kou/zulip,jackrzhang/zulip,brockwhittaker/zulip,Diptanshu8/zulip,dawran6/zulip,jainayush975/zulip,zulip/zulip,punchagan/zulip,TigorC/zulip,zulip/zulip,kou/zulip,jainayush975/zulip,Vallher/zulip,jphilipsen05/zulip,joyhchen/zulip,jphilipsen05/zulip,AZtheAsian/zulip,sonali0901/zulip,hackerkid/zulip,dattatreya303/zulip,peiwei/zulip,zulip/zulip,arpith/zulip,Jianchun1/zulip,calvinleenyc/zulip,showell/zulip,Juanvulcano/zulip,paxapy/zulip,timabbott/zulip,TigorC/zulip,KingxBanana/zulip,PhilSk/zulip,PhilSk/zulip,eeshangarg/zulip,niftynei/zulip,Diptanshu8/zulip,christi3k/zulip,Juanvulcano/zulip,TigorC/zulip,SmartPeople/zulip,umkay/zulip,calvinleenyc/zulip,brainwane/zulip,vaidap/zulip,dhcrzf/zulip,arpith/zulip,krtkmj/zulip,andersk/zulip,Jianchun1/zulip,isht3/zulip,dattatreya303/zulip,brainwane/zulip,ryanbackman/zulip,dattatreya303/zulip,punchagan/zulip,kou/zulip,andersk/zulip,dhcrzf/zulip,jainayush975/zulip,joyhchen/zulip,showell/zulip,KingxBanana/zulip,isht3/zulip,sup95/zulip,eeshangarg/zulip,JPJPJPOPOP/zulip,jackrzhang/zulip,AZtheAsian/zulip,samatdav/zulip,amyliu345/zulip,showell/zulip,isht3/zulip,showell/zulip,jackrzhang/zulip,rht/zulip,SmartPeople/zulip,j831/zulip,Jianchun1/zulip,timabbott/zulip,dhcrzf/zulip,hackerkid/zulip,jphilipsen05/zulip,dawran6/zulip,dhcrzf/zulip,grave-w-grave/zulip,niftynei/zulip,jackrzhang/zulip,sharmaeklavya2/zulip