Issue #31: Make sure to check that the media player is in a valid state

There are some cases where the media player has been released before one
of the required requests has been completed, so need to make sure the
media player is in a valid state before we do anything.
Issue #30: Handle Poster or Background image being null.

There are cases where the meta data is incomplete and no poster or
background image is provided.  In these cases need to default to the
standard image and load it.  Need to check for Null so we avoid NPE.
Release 0.9.1.