[Major] Implemented CACHED mode

This lead to refactoring of other code:
 - removed get*Dao() from StrolchTransaction
 - added StrolchTransaction.getPersistenceHandler()
 - removed unused variables in TransactionalElementMap
   - this lead to removal of constructors in subclasses
 - added ComponentContainer.getDataStoreMode()
 - added ElementMap.addAll(), removeAll() and updateAll() methods
   - implemented in all ElementMap implementations