Remove dead code.
Add some X-Plex headers more often, fixes #213.
Fetch server details for shared servers as well, fixes #234.

We were previously only requesting the root XML for owned servers, which
meant that we had no idea about the capabilities of shared servers. Now
we request the root XML from shared servers as well, so that we know
what sort of transcoding support they offer.
Bump version to 2.6.4, add release notes.