added new tagging variables and new version of CombinedSVComputer
minor fixes
combined CSVV2+SL tagger
changes needed or combined CSVV2_SL tagger
if-else instead of ifs and removing the unneeded exception
Merge pull request #2622 from cms-btv-pog/CSVnewVars_from-CMSSW_7_1_0_pre2

btag algorithms -- Changes needed for new btag algorithms