switch back to use associator for track validation
Avoid segfault in playback mode if no files specified
Merge pull request #2716 from wmtan/AvoidPlaybackSegfaultOnEmptyFileList

Misc fixes -- Avoid segfault in playback mode if no files specified
Merge pull request #2710 from cerati/fix-track-valid-bug-71X

DQM -- Switch back to use associator for track validation
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X