scripts: Add script to autogenerate a self-signed SSL cert.
scripts: Add script to autogenerate a self-signed SSL cert.

This will simplify step 1 of prod-install instruction to reduce
suffering in testing/experimenting production environments.

Attribution: the scripts/setup/configure-certs is based on @galexrt's
https://github.com/zulip/zulip/pull/450/commits/5c0daf62114b8ae7bd16f317a1883fd5f421d906

Further tweaked by tabbott to rename the script and edit the messages.

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