Globe tree

Hi Seth,

As discussed this morning, sending a cheeky pull request with all the variables in the tree apart from the event interpretation and config params. In the end, all the gen level info I needed was available from miniAOD...

I did fetch upstream and rebased, and it compiled fine.

(PS note i have modified photon.h, photon.cc and photonProducer.cc to add a couple of methods for isolation cone size).