OGM-358 Add MongoDB native queries test
OGM-358 Add native queries support
OGM-358 Move DatastoreProvider#executeBackendQuery(...) method to the GridDialect
OGM-358 Remove unused function getSession() in OgmEntityManager
OGM-358 Throwing exception when trying to execute native queries on Ehcache
Merge branch 'master' of https://github.com/hibernate/hibernate-ogm