Hgc digigeom

This version of the digitizer contains the ganging of the SimHit DetIds complying with the changes made for SLHC14 by @bsunanda and some new features.
I tested with runTheMatrix.py -w upgrade -l 12200 and found now problems in step2
Is there a chance that this can still make it for SLHC14? Otherwise the RecHits for HGC will have wrong DetId assignments.

@vandreev11, @amagnan follow this as well