Do not create unnecessary Picasso objects.

Address "java.lang.IllegalStateException: Too many receivers"
exceptions.  (See Issue #145).  Each new Picasso object registers its
own NetworkBroadcastReceiver.  Worse, we create a new Picasso object
each time we transform an AlbumCover image.  So do not create
unnecessary Picasso objects.

Rather than depend on receiving a Context object when called to load
an cover art, fetch the Application context as returned from FFA.get()
at singleton construction time.  The Application context is long
lived.

This has an additional advantage.  Not generation new Picasso objects
for each CoverArt image avoids holding a reference to an object that
cannot, later, be garbage collected.