Conform to codingstandards,  add documentation and put MediaCreatorService in the container.

There are 2 small breakingchanges. The constants have been fully uppercased and the getEntityManager function was removed (seemeed useless and a silly way to get to the EntityManager)
Merge pull request #113 from Kunstmaan/feature_document_mediacreatorservice_codingstandards

Docs, CodingStandards & add to service for MediaCreatorService