Refactor Avalon Music Server to be a WSGI application and CLI scripts instead of stand-alone server

* Change app to use Flask framework
* Split out scanning functionality into avalon-scan
* Create proper configuration files for the app (settings.py)
* Include reference configurations for Gunicorn, uWSGI, and Supervisord
* Include Fabric deploy script
* Work on supporting Python 3.3 and 3.4 (potentially)
* Change unit tests to use Nosetests