hltGetConfiguration: wrap list of input files longer than 255 elements
hltGetConfiguration: add an option to specify the parent input files or dataset
Merge pull request #6753 from fwyzard/hltGetConfiguration-improve-input

hltGetConfiguration: improve handling of input files and datasets
Merge remote branch 'origin/CMSSW_7_4_X' into CMSSW_7_0_X