Make sure all resources are closed #30

Created CloseableDB interface that extends DB - contains a close() method
Data now implements CloseableDB - call to close closes RAF in DBAccessor
DataRemoteAdapter updated with close() method also
DataRemoteAdapterImpl close() calls close() in the CloseableDB instance it wraps
Added cleanUp() method to BusinessService - it calls CloseableDB.close()
Added closeDatabaseConnection() method to Server