Add Google Analytics v3

v3 for backwards compat. We should be logging out exceptions (both
caught and uncaught), screen views, and some key usage metrics.

The dispatch interval is left at the default (30 minutes). I'm not
exactly sure how that works if the app isn't in the foreground. I think
it will go. I guess we'll wait and see.
Pack-specific graphics

If we know what pack image to use for a pack, use it.

Also introduces the ART directory for keeping track of design assets.
Logging to answer hypothesis

Do users expect to be able to tap a selected pack again to disable it?