Account: Implement Idendity trait (the PasswordInfo part)

This will enable Account to be used with securesocial.
oAuth{1,2}Info is still missing
UserStore: use JPA and Account for user storage

Replaces the Anorm based user storage.
UserStore: Fix deleteExpiredTokens (before vs. after)

We want to delete all tokens that have an expiration time that
is before now, i.e. small then now.
Merge pull request #29 from gicmo/user_db

Port UserStore to Account + JPA

Great: less ugly than expected :-)