Changing FetchType to EAGER in Group model

To prevent a LazyInitializationException when requesting the app-context
with a logged in user the FetchMode of the Group-User- and the
Group-Module-relationship is changed to EAGER.
Revert previous commit

Set FetchType back to LAZY in Group model due to performance issues.
Fetching modules of user within same transaction.

To prevent a LazyInitializationException while getting the app-context the
modules of a user are fetched within the same transaction.
Merge pull request #49 from chrismayer/master

Avoiding LazyInitializationException when executing getUsers() or getModules()