update DbsUrl to point to DBS3
Merge pull request #2440 from franzoni/from-CMSSW_7_0_X_2014-02-12-1400_DbsUrl

Configuration/PyReleaseValidation -- validation matrix update DbsUrl to point to DBS3
Merge remote branch 'origin/CMSSW_7_0_X' into CMSSW_7_0_X