SDK only: integrate new sample code, deprecating along the way.

The new support library features and sample code for switching
between fragments using a TabHost now eliminates the utility of
the TabActivity class, so deprecate it.  This also means there is
no longer any use in ActivityGroup or LocalActivityManager.  Yay.

Also fix up things so the new support API demos are included in
the documentation.

Change-Id: I4f073b82787f32560ba1fa5b6a23746ecc8aecdc