Fixed memory problem in PrimaryVertexAnalyzer4PU

PrimaryVertexANalyzer4PU was allocating an array of arrays using new[] but failed to use delete[]. The problem was found by the static analyzer. Rather than fix the fragile delete, I switched to code to use container objects which manage their own memory. This also meant changing a function to return a std::vector<int> rather than an int* and requiring the caller to remember to delete the item (there wrong delete was being used there anyway).
Merge pull request #1793 from Dr15Jones/fixMemoryProblemInPrimaryVertexAnalyzer4PU

Falidation fix -- Fixed memory problem in PrimaryVertexAnalyzer4PU