Work on issue #17628623: Need to update default preferred activities for YouTube

Improve the warning logs when setting up preferred activities
to help identify when there are issues and what they are.  Also
improve the algorithm a little to still apply permissions when
resetting them and there are additional third party apps, as long
as the additional app is something like another browser and the
preferred activity being set is more specific (has a better match).

And add an example of using manifest-based preferred activities
in to ActivityTest -- and yes it DOES work! :p

Change-Id: I1ff39e03a5df6526206e0c3882085396b355d814