Let webapp compress status.json if client supports it

Currently status.json is about 1.5 Mb. It can easily be compressed down
to ~115Kb which will make clients' life easier.
Also changed webapp to be a proper WebOb app to remove new wheels in
code.

Change-Id: I400c6133627a82af1c702df78ae688ed89fff0bb
Merge "Let webapp compress status.json if client supports it"