provision: Simplify messaging in tools/provision.
provision: Simplify messaging in tools/provision.

The script now outputs bullet points to the user when
it fails, and there are some basic comments at the top
of the file.  I also fixed the path of the log file.

Fixes #3230

dattatreya303/zulip,ryanbackman/zulip,SmartPeople/zulip,christi3k/zulip,jackrzhang/zulip,shubhamdhama/zulip,vabs22/zulip,zulip/zulip,vaidap/zulip,dawran6/zulip,jainayush975/zulip,brainwane/zulip,mahim97/zulip,jainayush975/zulip,SmartPeople/zulip,jrowan/zulip,christi3k/zulip,jphilipsen05/zulip,rht/zulip,dawran6/zulip,blaze225/zulip,aakash-cr7/zulip,verma-varsha/zulip,susansls/zulip,christi3k/zulip,dattatreya303/zulip,jrowan/zulip,andersk/zulip,rishig/zulip,jackrzhang/zulip,eeshangarg/zulip,shubhamdhama/zulip,isht3/zulip,vaidap/zulip,Galexrt/zulip,brockwhittaker/zulip,zulip/zulip,vabs22/zulip,rishig/zulip,mahim97/zulip,synicalsyntax/zulip,samatdav/zulip,ryanbackman/zulip,blaze225/zulip,mahim97/zulip,JPJPJPOPOP/zulip,rht/zulip,PhilSk/zulip,aakash-cr7/zulip,brainwane/zulip,timabbott/zulip,isht3/zulip,zulip/zulip,dawran6/zulip,hackerkid/zulip,PhilSk/zulip,souravbadami/zulip,jainayush975/zulip,shubhamdhama/zulip,SmartPeople/zulip,rishig/zulip,andersk/zulip,mahim97/zulip,souravbadami/zulip,tommyip/zulip,brockwhittaker/zulip,souravbadami/zulip,dawran6/zulip,showell/zulip,JPJPJPOPOP/zulip,timabbott/zulip,Galexrt/zulip,mahim97/zulip,jackrzhang/zulip,sonali0901/zulip,vaidap/zulip,rht/zulip,synicalsyntax/zulip,punchagan/zulip,shubhamdhama/zulip,mahim97/zulip,andersk/zulip,SmartPeople/zulip,dhcrzf/zulip,souravbadami/zulip,JPJPJPOPOP/zulip,timabbott/zulip,aakash-cr7/zulip,christi3k/zulip,tommyip/zulip,isht3/zulip,dattatreya303/zulip,dhcrzf/zulip,PhilSk/zulip,susansls/zulip,tommyip/zulip,showell/zulip,verma-varsha/zulip,eeshangarg/zulip,rishig/zulip,hackerkid/zulip,brainwane/zulip,isht3/zulip,vaidap/zulip,blaze225/zulip,hackerkid/zulip,j831/zulip,synicalsyntax/zulip,brockwhittaker/zulip,rishig/zulip,samatdav/zulip,synicalsyntax/zulip,andersk/zulip,punchagan/zulip,Galexrt/zulip,rht/zulip,shubhamdhama/zulip,JPJPJPOPOP/zulip,SmartPeople/zulip,rht/zulip,isht3/zulip,jackrzhang/zulip,andersk/zulip,ryanbackman/zulip,JPJPJPOPOP/zulip,kou/zulip,sharmaeklavya2/zulip,jphilipsen05/zulip,kou/zulip,andersk/zulip,blaze225/zulip,eeshangarg/zulip,sonali0901/zulip,brockwhittaker/zulip,jackrzhang/zulip,blaze225/zulip,amanharitsh123/zulip,jrowan/zulip,zulip/zulip,rht/zulip,samatdav/zulip,eeshangarg/zulip,showell/zulip,verma-varsha/zulip,dhcrzf/zulip,dattatreya303/zulip,kou/zulip,dawran6/zulip,showell/zulip,souravbadami/zulip,punchagan/zulip,jainayush975/zulip,eeshangarg/zulip,brockwhittaker/zulip,amanharitsh123/zulip,timabbott/zulip,verma-varsha/zulip,jphilipsen05/zulip,susansls/zulip,sonali0901/zulip,sharmaeklavya2/zulip,souravbadami/zulip,brainwane/zulip,christi3k/zulip,PhilSk/zulip,sonali0901/zulip,PhilSk/zulip,verma-varsha/zulip,jphilipsen05/zulip,tommyip/zulip,jainayush975/zulip,Galexrt/zulip,jphilipsen05/zulip,jrowan/zulip,vabs22/zulip,christi3k/zulip,punchagan/zulip,blaze225/zulip,punchagan/zulip,aakash-cr7/zulip,sonali0901/zulip,ryanbackman/zulip,susansls/zulip,rishig/zulip,dhcrzf/zulip,synicalsyntax/zulip,zulip/zulip,dhcrzf/zulip,dattatreya303/zulip,punchagan/zulip,punchagan/zulip,timabbott/zulip,zulip/zulip,andersk/zulip,showell/zulip,synicalsyntax/zulip,brainwane/zulip,tommyip/zulip,j831/zulip,amanharitsh123/zulip,showell/zulip,susansls/zulip,jrowan/zulip,vaidap/zulip,shubhamdhama/zulip,jphilipsen05/zulip,aakash-cr7/zulip,sharmaeklavya2/zulip,sonali0901/zulip,PhilSk/zulip,amanharitsh123/zulip,rht/zulip,aakash-cr7/zulip,hackerkid/zulip,sharmaeklavya2/zulip,hackerkid/zulip,vaidap/zulip,jainayush975/zulip,jackrzhang/zulip,dhcrzf/zulip,kou/zulip,dattatreya303/zulip,hackerkid/zulip,brainwane/zulip,j831/zulip,timabbott/zulip,amanharitsh123/zulip,j831/zulip,vabs22/zulip,zulip/zulip,kou/zulip,hackerkid/zulip,vabs22/zulip,samatdav/zulip,JPJPJPOPOP/zulip,dhcrzf/zulip,Galexrt/zulip,eeshangarg/zulip,showell/zulip,amanharitsh123/zulip,brainwane/zulip,eeshangarg/zulip,jrowan/zulip,synicalsyntax/zulip,jackrzhang/zulip,samatdav/zulip,kou/zulip,j831/zulip,rishig/zulip,sharmaeklavya2/zulip,dawran6/zulip,susansls/zulip,brockwhittaker/zulip,vabs22/zulip,kou/zulip,tommyip/zulip,samatdav/zulip,shubhamdhama/zulip,tommyip/zulip,ryanbackman/zulip,timabbott/zulip,Galexrt/zulip,isht3/zulip,verma-varsha/zulip,SmartPeople/zulip,j831/zulip,sharmaeklavya2/zulip,ryanbackman/zulip,Galexrt/zulip