Massive realism upgrade.

Themes and styles are now supported!
Lots of shadow methods have been modified or removed entirely, for much more faithful SDK emulation.
Enum and flag attriburtes are parsed correctly.
Resource handling is generally much better.
Use Robolectric.buildActivity() for easy activity manipulation.
Activities are assigned a theme as specified in the app's manifest.
Don't let the Choreographer go into frame-scheduled mode.
Use real SDK code from ViewRootImpl and ActivityThread.
Better handling of references in resources.
Lots o' whitespace.
Added @Ignore to some tests that may not be valid in modern SDKs.
Added @Ignore to some tests that aren't working yet but seem of lower value.