Add models for each table in the database, plus User. Relates to #446

Basically, I went ahead and reconstructed each table in the database as
a mapping class. In addition, I recreated the User class that subclassed
Participant class previously.

There is still clean up that needs to be done here.

Signed-off-by: Joonas Bergius <joonas.bergius@gmail.com>
Made changes to the ORM-related configuration and access, added convenience methods
Moved authentication to use the ORM-based class
Added dependencies for the new ORM-based classes
Moving templates over to use the ORM classes where it makes sense
Moving some initial tests over, more to come.