This makes it so that media playback support for inputs is dynamically
fetched from the receiver, instead of assuming that all playback
commands work for all inputs.
Tests are added for this, using a FakeYamaha class, which has some
sample data stubbed in for key methods that need to be called. We also
include an example of the desc.xml needed to dynamically parse these
features for these tests (as this is done in platform init).
Johann Kellerman
Fabian Affolter
Sean Dague