hist/plt updates + bug fixes

[pmlugato]

worked with Joey and Luca on the following changes:

• added missing xsec for inclusive TTJets sample
• added single filelist with bkgd and signal for use at plotting stage (need to submit private signals and bkgds separately in producer)
• when making hists, new variables added THEN selections made (so you can select on new variables)
• added hists relevant to WH in hist_defs
• pileup, prefire, and PS weights applied for WH (previous revamp of plotting flow reverted this)
• TopPT -> HighestPT in make_hists config files
• xsecs applied correctly for WH private samples as well now
• saving git diffs works for submit.py now
• minor bug fixes/old comment removal