Added timezone awareness to the queue.

Also fixed a problem with authentication not working correctly anymore,
this now uses a subclass that special-cases GET requests.
Finished up track searching.

This also adds read-only APIs for Albums, Artists and Tracks
Finished up Songs API.

This adds a read-only API for the Songs entries with searching
support on the `metadata` field.
Accidently passed a second non-existant argument to `is_authenticated`.