Support for browsing "secondary" servers, fixes #227.

This fixes the crash caused by the iOS server version, and generally gets
mini server browsing working.
Use checkFiles=1 when refreshing metadata as well.
Show a specific error when transcoding isn't supported, fixes #231.
Account for query string when inferring audio codec, helps #228.
Tweak totally bogus exif check.

This check is totally bogus, but we don't have exif information in the XML yet
and this helps when browsing from iOS photos. The width vs. height check was the
reverse of what I meant to check, but it's not even going to be right that often.
And if iOS adds width/height before adding some exif information to key off of,
the photos are going to be transcoded for being unnecessarily large anyway. So
it seems fine all things considered to transcode anything for which we have no
information.
Check device info for surround support periodically, fixes #229.

The Roku 3 surround support can be a moving target because of the headphones in
the remote. So we can't just check at startup and remember the value anymore.
But reading the device info was observed to be slow, so we don't want to check
every time in the loop where we process video item XML. We use a simple timer
to refresh the value periodically, and make sure we have the current value before
we start to actually play a video.
Bump version to 2.6.3, add release notes.

Also, creating release notes in source control according to the proposed
Plex standard.
Don't include screenshots in the package, save 20kb.