Avoid segfault in playback mode if no files specified
Merge pull request #2718 from wmtan/AvoidPlaybackSegfaultOnEmptyFileList70X

Framework fix -- Avoid segfault in playback mode if no files specified
Merge remote branch 'origin/CMSSW_7_0_X' into CMSSW_7_0_X
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X