ArtCollectionEndpoint: fixing annotation problems. commented out faulty method addArtCollection(collection)
Included Apache licence header in source files
Reorganized pom.xml
Reorganized dao method declarations
Commented dao methods
Minor style changes
Entities are now serializable
Implemented caching mechanism, fixes #7
Fixed endpoint for creating an artcollection, fixes #1
Fixed uninitialized attribute
POST requests now return the modified entity's ID if successful, fixes #9
Overrided toString method in model classes