StreamingService: Prefer explicit imports.

The Android Team's Code Style Guidelines for Contributors says that explicit
imports must be used, and I think it's good common sense stuff.
StreamingService: Initialize remoteControlClient as RemoteControlClient.

Since we're beyond API 13, RemoteControlClient can be used rather than a
more generic object.
StreamingService: Add copyright header.
StreamingService: Remove onStart() stub.

onStart was depreciated in 2.0, should have gone away by now.
StreamingService: Explicit try/catch & remove/reverse conditionals.

The point of this commit is to remove the deep layers of nested conditionals
inside showNotification(). This will make this member easier to read and
improve. I do this by removing unnecessary conditionals and reversing/returning
conditionals as required.

This commit also removes the try/catch block which encompassed the entire
method. If we crash MPDroid because we're not handling exceptions, we need to
handle them and not paper over the problem, IMHO.
StreamingService: Don't assume that album, artist or title exist.

MPDroid's old behaviour when adding the album, artist or title to the
notification panel is if it's null the notification panel would print the
string 'null' to the notification panel.

The new behaviour checks for the field first, then is either omitted, as is the
case with album or artist, or is substituted with filename in the case of
the title tag.
StreamingService: Rename a couple of variables for readability.

Rename resumeStreaming() to beginStreaming() and oldStatus to prevMpdState
to improve the logical naming. They make more sense to me, I hope they do
for you as well.
StreamingService: Move all stubs to the end of the file.

Take the stubs out of the body of the code to increase readability.
StreamingService: Remove large nested blocks in stateChanged().

Removing large nested blocks improves readability.
StreamingService: Comment additions, cleanups and breathing space.

Add a few comments here and there, clean up some old comments and add some
space to increase readability.
StreamingService: Move coverart notification to it's own method.

Move the coverart stuff from showNotification() to it's own method. Also move
the MetadataEditor to the proper method, setMusicInfo(); this clears up a TODO
and should make things a little more clear for readability.