Improve /updateserver, /rebuild, /hotpatch UX
Improve /updateserver, /rebuild, /hotpatch UX

My carefully-designed `/updateserver` UX has been ruined by the
addition of the rebuild step.

The new `/updateserver`, `/rebuild`, and `/hotpatch` commands are now
once again as carefully-designed as before, and should represent a
much improved server administration experience.

sirDonovan/Pokemon-Showdown,xfix/Pokemon-Showdown,sirDonovan/Pokemon-Showdown,Zarel/Pokemon-Showdown,xfix/Pokemon-Showdown,Zarel/Pokemon-Showdown,xfix/Pokemon-Showdown,svivian/Pokemon-Showdown,xfix/Pokemon-Showdown,svivian/Pokemon-Showdown,Zarel/Pokemon-Showdown,svivian/Pokemon-Showdown,svivian/Pokemon-Showdown,xfix/Pokemon-Showdown,svivian/Pokemon-Showdown,sirDonovan/Pokemon-Showdown