Vetex selector as example algorithm (incl. base class, factory, etc etc)
rm commented out code
Merge pull request #4 from sethzenz/master

Add VertexSelector as an example algorithm
make select const, use unique_ptr for selector in DiPhotonProducer
Merge pull request #5 from sethzenz/master

make select const, use unique_ptr for selector in DiPhotonProducer
back to master
removed stuff