Small update of FastPV sequence

Small updates of the FastPrimaryVertex code and JetVertexChecker, presented at TSG meeting:
https://indico.cern.ch/event/338610/contribution/1/1/material/slides/0.pdf

In both Producer is possible to maintaing the "old" method, with the options:
- "newMethod" in JetVertexChecker
-  "m_ptWeighting" in FastPrimaryVertexWithWeightsProducer
No, m_ptWeighting_parameter is just a parameter used to parametrize the pT weight.

Using (pt-m_ptWeighting_parameter)/(40-m_ptWeighting_parameter) the pT weight is one for a jet with pT=40, just to put a momentum scale