Merge pull request #38 from camilocarrillo/master

Vertex ID Big commit 2
new pileupjetid validation variables
regression development and plotting
cleanup: rm debug msg, clarify README
Merge pull request #40 from sethzenz/dev_regression

Add regression (and some new validation variables)
cleaned code, reduced verbosity, map with mva variables built, returning vertex with max_mva_id