Merge pull request #64 from mdanter/master

Modified mySQL datasource JNDI names, added Oracle and Postgres sample datasource configuration
Merge pull request #66 from mdanter/master

Added LDAP and File based User Group Callback Implementation
Merge pull request #67 from mdanter/master

Corrected file based User Group Callback implementation.
Refactored to remove the database types.
Removed duplicate EntityManagerFactory.
Merge remote-tracking branch 'upstream/master'