Test move Podcast data to PostgreSQL

TODO
* [x] ~~use [``django.contrib.postgres.fields.ArrayField``](https://docs.djangoproject.com/en/dev/ref/contrib/postgres/fields/#arrayfield)~~ (will not be in Django 1.7)
* [x] Episode pagination (eg http://176.28.52.105:8002/podcast/logbuchnetzpolitik-mp3/-episodes?page=2) does not work