Bug fix for NewEventStreamFileReader

Make the inputFileTransitionsEachEvent option work
with NewEventStreamFileReader. This was accidently
broken in 2012, although as far as I know no one
normally uses this option with this source. It was
noticed when someone used the option to debug a
related problem in another source. Added a unit test
so we will notice if this problem recurs.

The bug caused the input file to be prematurely closed
when the fake input file transitions were occurring.
Merge pull request #6363 from wddgit/streamerFileTransitions

Bug fix for NewEventStreamFileReader
Merge remote branch 'origin/CMSSW_7_3_X' into CMSSW_7_0_X