Code review comment for lp:~matthew-pirocchi/pyroom/use-gtkbuilder-fixed

This is the fixed version of this merge proposal:
https://code.launchpad.net/~matthew-pirocchi/pyroom/use-gtkbuilder/+merge/9991
It's in a separate branch because I forgot to check in one of the files in the old branch, and had since deleted it. I think this branch is cleaner anyway, and I divided the commits up better this time, so it works out.

Copied from the old proposal:
"PyRoom currently uses libglade for loading glade files. This is deprecated as of GTK+ 2.12 (see http://live.gnome.org/GnomeGoals/RemoveLibGladeUseGtkBuilder). Instead, applications should use GtkBuilder, which is now built into gtk (unlike libglade, which is a separate library).

I've refactored PyRoom to use GtkBuilder instead of libglade."

Note:
The two RuntimeWarnings are because there are two signals in the preferences gladefile that are not handled. They weren't handled in libglade either, but libglade didn't warn you about this. This probably means you don't use them for anything, but I figured I'd stick to a simple refactoring and let you take a look and see if you want to get rid of them.