Restore the code for adding admin widgets.
Restore the code for adding admin widgets.

The code for adding widgets in the administration UI disappeared due to
a merge earlier this year. This went unnoticed by us until today. This
is a simple change that restores the missing lines.

chipx86/reviewboard,sgallagher/reviewboard,davidt/reviewboard,brennie/reviewboard,chipx86/reviewboard,reviewboard/reviewboard,chipx86/reviewboard,sgallagher/reviewboard,davidt/reviewboard,brennie/reviewboard,sgallagher/reviewboard,brennie/reviewboard,sgallagher/reviewboard,reviewboard/reviewboard,chipx86/reviewboard,brennie/reviewboard,davidt/reviewboard,davidt/reviewboard,reviewboard/reviewboard,reviewboard/reviewboard