Use conditions DB v2 (72x)

As requested, here is the PR with more meaningful names for the new conditions DB ("condDBv2"). 
Added is also the change in runTheMatrix to use the condDBv2 files by default (via the new '--useCondDBv2' option of cmsDriver)
Hmm, shouldn't the "CMS_COND_31X_L1T" part here and in the following be replaced by "CMS_CONDITIONS" everywhere as well?