v0.4.41 logging added. Split database into a base class db_base with general...

v0.4.41 logging added. Split database into a base class db_base with general methods and nfvo_db with openmano specific methods

Change-Id: Iad677a18e96692b3eab28e73c2fc5cd36a13ae1f
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>