Work on issue #21516866: Implement voice interaction in ResolverActivity

The main change here is to not allow the dialog to go in to its "focus
on the last app the user selected" when running in voice interaction mode,
instead just always giving a simple list.

This also fixes some problems with cleaning up active commands when
an activity finishes and not forcing the current session to go away
when the screen is turned off.

Also added some debug help, having activity print the state of the
voice interactor.

Change-Id: Ifebee9c74d78398a730a280bb4970f47789dadf5