Gerrit/personal sandbox

Gerrit allows the creation of "personal sandboxes" where users can stash code that they're working on in a personal branch that doesn't require admin intervention for pushes. These personal sandboxes are not intended to replace standard Gerrit/Git branches where multiple people can collaborate on code.

The branches are named in the format "sandbox/$username/*" so I could make a sandbox called "sandbox/demon/weekend-hacking" and push that to gerrit without requiring review or anyone to make the branch first. Quick example:

$ cd mediawiki/core

$ git checkout -b sandbox/demon/foo-bar

When you're ready to push: $ git push --set-upstream origin sandbox/demon/foo-bar

(The --set-upstream is only necessary the first time you push.)