from 53X: added support for default compiler and extra tools
Merge pull request #924 from smuzaffar/IB/CMSSW_7_0_X/stable

from 53X: added support for default compiler and extra tools
Merge remote-tracking branch 'origin/IB/CMSSW_7_0_X/stable' into IB/CMSSW_7_0_X/stable
Merge remote-tracking branch 'origin/IB/CMSSW_7_1_X/stable' into IB/CMSSW_7_0_X/stable
Merge remote-tracking branch 'origin/IB/CMSSW_7_2_X/stable' into IB/CMSSW_7_0_X/stable