Merge pull request #292 from pedroigor/master

[PLINK-443] - JPAIdentityStore looks for Id.class instead of Identity.class.
Merge pull request #293 from pedroigor/master

[PLINK-441] - Identity Model classes no-arg constructors must be public.
Merge pull request #294 from pedroigor/master

[PLINK-436] - Identity.hasPermission(class, identifier) does not work with a JPA store.