Merge pull request #15 from stoewer/master

Improve models and JPA configuration

LGTM
[sbt] add jdbc and anorm dependencies
[auth] add to/from DateTime converter for anorm
[db] Add database evolution for user and token tables
[auth] Replace InMemUserStore with db-backed store
Merge pull request #16 from gicmo/user_db

Looks OK
Merge pull request #17 from stoewer/master

ConferenceService: started implementation

LGTM
Merge pull request #18 from stoewer/master

DBUtil: utility functions for classes and tests with JPA

LGTM