update matrix : fixes and DQMio

.          DQMROOT => DQMIO needs be extended to teh cmsDriver
.         when using dqmio, set NEW! datatier name to DQMIO (in place of old DQMROOT)
.         two new workflows GEN-SIM only, to prepare input of pileup workflows which don't have a no-pileup correspondent ; thanks to @fabozzi (ZmumuJets_Pt_20_300 and ZmumuJ
.         gen2015 for ZmumuJets_Pt_20_300_13 => get correct GT (thanks to @fabozzi and @ferro)

.         NOTE: access to sim geometry left purposefully xml-based for postLS1 samples, for consistency with the 70x cycle.