Add log config.

Logging configuration is stored in separate yaml files, and might vary
in different environments, and is thus configurable through the
LOG_CONF_PATH configuration variable. We disallow starting the app
without this parameter set, to make sure it's detected early if this
happens in production. This is ignored though if either the DEBUG
or the TESTING config var is True.
Add movie search.

Only searches movie titles for now, but that should be sufficient for
most use cases. No ranking of results, I have no idea what order they
will be retrivied in.
Remove POST creation of movies.

Not intended as a permanent solution, but we'll reimplement this later.

For now we want all movies to be loaded automatically, the functionality
for this will be added quite soon(tm).
Fatten up Movie model. Add fields for category, year, external_id.

Also datetime_added.

Make to to_json methods accept a include_streams parameter to
customize object serialization, for both movies and streams.

Movies now require the external_id attribute to be present, so
added that field to all movies created in the test suites.
Add asynchonous loading of movies from OMDB.

Use Celery to run tasks asynchronously. New required setting:
CELERY_BROKER_URL.

Also made the grunt nose task stop on first test failure.

Tests are now run against a fixed-name temp name, to make sure that
the asynchronous tasks re-use the same db as the app that spawned them.
If there's any better solutions to this, please fix.
Make prints py3 compatible.