provisioning: Add version warning for Vagrant 1.8.7.
provisioning: Add version warning for Vagrant 1.8.7.

Vagrant 1.8.7 is not supported due to broken curl, see
https://github.com/mitchellh/vagrant/issues/7997 for reference.

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