This change adds a new extension hook, the UserInfoBoxHook, which allows

extensions to inject additional data into the infobox. This is shown in a new

panel below the existing information, so it doesn't screw up the existing

layout.
This also fixes up a couple bugs in my earlier redesign change that emerged as

I tested it with this.

Built a simple extension which lists a count of the users' incoming and

  outgoing review requests in the infobox and saw the correct results.
Ran unit tests.