Update changelog since the Zulip 1.5 release.
Update changelog since the Zulip 1.5 release.

It's amazing how much we've done in the last few months.

punchagan/zulip,jackrzhang/zulip,zulip/zulip,brainwane/zulip,j831/zulip,brockwhittaker/zulip,mahim97/zulip,brainwane/zulip,synicalsyntax/zulip,andersk/zulip,brainwane/zulip,kou/zulip,rishig/zulip,vabs22/zulip,brainwane/zulip,vaidap/zulip,timabbott/zulip,amanharitsh123/zulip,Galexrt/zulip,mahim97/zulip,shubhamdhama/zulip,shubhamdhama/zulip,eeshangarg/zulip,rishig/zulip,showell/zulip,andersk/zulip,jphilipsen05/zulip,dhcrzf/zulip,andersk/zulip,kou/zulip,kou/zulip,zulip/zulip,vabs22/zulip,kou/zulip,verma-varsha/zulip,vabs22/zulip,rishig/zulip,tommyip/zulip,vaidap/zulip,jrowan/zulip,punchagan/zulip,hackerkid/zulip,Galexrt/zulip,timabbott/zulip,tommyip/zulip,mahim97/zulip,ryanbackman/zulip,punchagan/zulip,timabbott/zulip,vabs22/zulip,jackrzhang/zulip,andersk/zulip,Galexrt/zulip,timabbott/zulip,Galexrt/zulip,tommyip/zulip,verma-varsha/zulip,dhcrzf/zulip,j831/zulip,punchagan/zulip,brockwhittaker/zulip,zulip/zulip,hackerkid/zulip,jackrzhang/zulip,verma-varsha/zulip,showell/zulip,Galexrt/zulip,rht/zulip,dhcrzf/zulip,rht/zulip,jackrzhang/zulip,eeshangarg/zulip,verma-varsha/zulip,punchagan/zulip,verma-varsha/zulip,jphilipsen05/zulip,eeshangarg/zulip,amanharitsh123/zulip,ryanbackman/zulip,zulip/zulip,dhcrzf/zulip,christi3k/zulip,brockwhittaker/zulip,brainwane/zulip,dhcrzf/zulip,showell/zulip,hackerkid/zulip,synicalsyntax/zulip,kou/zulip,showell/zulip,eeshangarg/zulip,showell/zulip,andersk/zulip,amanharitsh123/zulip,shubhamdhama/zulip,amanharitsh123/zulip,rht/zulip,christi3k/zulip,punchagan/zulip,synicalsyntax/zulip,punchagan/zulip,synicalsyntax/zulip,vaidap/zulip,mahim97/zulip,timabbott/zulip,jphilipsen05/zulip,synicalsyntax/zulip,jrowan/zulip,tommyip/zulip,jackrzhang/zulip,j831/zulip,jphilipsen05/zulip,synicalsyntax/zulip,shubhamdhama/zulip,tommyip/zulip,synicalsyntax/zulip,rishig/zulip,shubhamdhama/zulip,tommyip/zulip,jackrzhang/zulip,jphilipsen05/zulip,andersk/zulip,christi3k/zulip,mahim97/zulip,verma-varsha/zulip,showell/zulip,kou/zulip,shubhamdhama/zulip,vabs22/zulip,brainwane/zulip,kou/zulip,christi3k/zulip,tommyip/zulip,j831/zulip,showell/zulip,ryanbackman/zulip,amanharitsh123/zulip,rishig/zulip,hackerkid/zulip,jrowan/zulip,zulip/zulip,brockwhittaker/zulip,vaidap/zulip,rishig/zulip,jrowan/zulip,timabbott/zulip,eeshangarg/zulip,brockwhittaker/zulip,eeshangarg/zulip,j831/zulip,eeshangarg/zulip,dhcrzf/zulip,rht/zulip,ryanbackman/zulip,hackerkid/zulip,hackerkid/zulip,Galexrt/zulip,rht/zulip,ryanbackman/zulip,Galexrt/zulip,timabbott/zulip,brainwane/zulip,jackrzhang/zulip,brockwhittaker/zulip,jrowan/zulip,andersk/zulip,zulip/zulip,rht/zulip,vaidap/zulip,j831/zulip,mahim97/zulip,jphilipsen05/zulip,zulip/zulip,rishig/zulip,dhcrzf/zulip,christi3k/zulip,jrowan/zulip,shubhamdhama/zulip,ryanbackman/zulip,rht/zulip,christi3k/zulip,amanharitsh123/zulip,vabs22/zulip,vaidap/zulip,hackerkid/zulip