Update of the DeMo suite : new DeMoAtlasLoss script + minor improvements

Hello,

The DeMo suite is meant to monitor the defects set in the database: https://atlasdqm.web.cern.ch/atlasdqm/DeMo/

It is a standalone suite of python scripts. I am the only developer.

The MR includes several minor improvements and a new feature to compute the combined ATLAS inefficiency (new script DeMoAtlasDataLoss).

Thanks in advance

Benjamin