Merged refs/pull/3973/head from repository cms-sw
introduced SLHCUpgradeSimulations/Configuration/postLS1CustomsPreMixing wherever needec by premix workflows; TEMPORARY
 --geometry Extended2015  as needs be in the 70x (all GT-driven in subsequent releases)
process string set to differentiate 25ns/50ns pilep overlaid when done with premixed events
HARVEST in place of HARVESTCOS
new premixed dataset as for https://hypernews.cern.ch/HyperNews/CMS/get/relval/2998.html
RECOPRMXUP15PROD
prod premix wf's given different label to avoid dataset collision; assure RECO of prod premix workflows use consistent GT
Merge pull request #4001 from franzoni/from-CMSSW_7_0_X_2014-05-23-0200-premixPROD2

premix relvals: adapt to fixes of premixing