Add blacklist and purple list checks to CA-based GENtoEVGEN skeleton
Compared to the previous check I
- merged the black-list and purple-list check into a single function
- removed the check for the release flavour (which was always set to
AthGeneration)
One thing to discuss is whether and how to remove the hard-coded cvmfs path. We could see if we could put these two files in DATAPATH.