* All mongoDataAccess methods now return the latest versions of the entities
* Added class SubclassAwareMongoTemplate that overrides several MongoTemplate
  methods so that fetching by superclass would be possible
* Remove commit(ID) method from IPublisher
* Changed tabs to spaces
* IDataAccess.getMetadata takes an ID instean of an objects as an
  argument
* Added getAllBySupertype method to IDataAccess
* MongoDataAccess implements it by scanning the classpath for the
  whole hierarchy of EntityInstance descendants
* Spring MongoTemplate should be used as a default backend for
  MongoDataAccess. In case there are problems with superclasses
  SubclassAwareMongoTemplate can still be plugged in, though its
  performance will be worse
* Most Catalogue methods use getAllBySupertype