The new media button receiver with only a pending intent (no
component name) could be left hanging if the process that
registered it went away. These semantically need to be tied
to the calling process's lifetime; we now clean them up when
the calling process goes away.
Also added some additional cleanup of media button receivers
when packages change (updated, cleared).
And on top of that, a new "media" command for doing media
things. Currently lets you send media keys and monitor
remote display data.
Oh and finally added a new BaseCommand base class for
implementing these command line utilities.
Change-Id: Iba1d56f10bab1eec4a94a7bb1d1c2ae614c8bcf5