Set up IBs for CMSSW_7_4_DEVEL_X

I created branch CMSSW_7_4_DEVEL_X from CMSSW_7_4_X
In cmssw:
https://github.com/cms-sw/cmssw/compare/CMSSW_7_4_DEVEL_X...CMSSW_7_4_X
In cmsdist:
I created branch IB/CMSSW_7_4_X/next from IB/CMSSW_7_4_X/stable
https://github.com/cms-sw/cmsdist/compare/IB/CMSSW_7_4_X/next...IB/CMSSW_7_4_X/stable