[v6r11] Some fixes for WMS

There are also changes to comply to the Data Model https://docs.python.org/2/reference/datamodel.html#object.__nonzero__ for the RMS and DMS, that was causing a real bug (RequestName was wrongly set in FailoverRequest.py)

Some (old, broken) test files for WMS DBs have been removed and are now in TestDIRAC