Merge pull request #4971 from syuvivida/72x_20140815_weight

Codes require to save generator cross section in each luminosity block
Merge pull request #5601 from syuvivida/73x_fixXSec_eiko

GeneratorInterface -- Codes that fix the cross section computation
improve printout in GenXSecAnalyzer and add to default filter summary sequence
add missing dictionary for GenLumiInfoProduct data member
skip cross-section calculation if GenLumiInfo is not available (eg for single particle gun)
threading improvements
move from cout to LogPrint
don't exclude resonance decay products from gen jets, since this cannot in fact be done in a robust and generator-agnostic way
Merge pull request #5640 from bendavid/genxsec_genjets_71x

Backport of Cross Section machinery and GenJet config change to 71x
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X