Fixed new fast pv3

It is the same as the closed PR #1918 (by  @silviodonato and @arizzi):
- definition of two new producer modules, one for fast primary vertex in RecoPixelVertexing/PixelVertexFinding and one jet producer in HLTrigger/JetMET, in view of their usage for forthcoming HLT developments

It also takes into account all the fixes proposed by Slava, including the displacement of the jet producer PixelJetPuId to HLTrigger/JetMET.

It is safe to include it in the 7_0_X release as none of the present modules or classes gets ouched, and none of the possible present workflows will be affected. For the same reason, it cannot be tested with the present workflows or addon tests (this is just FYI).