Merge pull request #229 from ktf/master

Misc improvements.
Set up IBs for CMSSW_7_4_ROOT6_X
Merge pull request #230 from nclopezo/add-74-root6-ibs

Set up IBs for CMSSW_7_4_ROOT6_X
Merge pull request #231 from ktf/master

Misc cleanups to PR testing.
Do not assume scripts are in $WORKSPACE.