New mva taggers backport from 71X to 62XSLHC

Backport of the merged 71X pull requests:
https://github.com/cms-sw/cmssw/pull/2622
https://github.com/cms-sw/cmssw/pull/3384
https://github.com/cms-sw/cmssw/pull/3664
https://github.com/cms-sw/cmssw/pull/3733
but with changes in configuration files and CombinedSVComputer.cc to keep the standard CSV without a change