Revert "Disabling Google Logs (glog).  Be sure to reverse this commit should we find ourselves in a position to use it again."

This reverts commit cda463e8db64599f2c6e49d1455663339c1524b9.

Conflicts:
	distro/src/sconscript
Fixing lp:981829.

There was a segfault on Bounding Box unload.  This was a two parter:
 1. There was a logic error which allowed the CMO's drawable to be
 unloaded.  The CMO must *always* be in scope.

 2. We were unloading drawables ready for deletion in the
 Screen::prepare() stack of calls.  This is not the right place for
 Drawable deletion because Drawables themselves would be triggering
 their own deletion--which in turn causes segfaults.