Make Rivet 2.0.0 the default and only rivet.
Fix toolfile name.
Merge pull request #777 from degano/rivet2_default_72X

Rivet 2.0.0 default Rivet in 7_2_X
default SCRAM_ARCH for slc6 is now slc6_amd64_gcc481; default arch for any unknow system is slc6_amd64_gcc481; revision updated to be 1117
Merge remote branch 'origin/IB/CMSSW_7_0_X/stable' into IB/CMSSW_7_0_X/stable
Merge remote branch 'origin/IB/CMSSW_7_1_X/stable' into IB/CMSSW_7_0_X/stable
Merge remote branch 'origin/IB/CMSSW_7_2_X/stable' into IB/CMSSW_7_0_X/stable