Monojet photon ID

Updated photon related classes to the Hgg latest, which got lost in the commit 0775f7cf6b2f5a02214b4ac022f2b308d53d9000 of Feb 14. Unfortunately, this removes all the updates and clean up that happened between then and now.  The most critical things seem to be the paths to the weight files, which used to be relative to CMSSW_BASE and are now relative to MIT_DATA. This commit uses the old style again (CMSSW_BASE).

Also, the newest weight files for the MVA photon ID need to be added to MitPhysics/data.  They can be copied from t3btch*:
/home/veverka/cms/cmssw/032/CMSSW_5_3_14/src/MitPhysics/data/2013FinalPaper_PhotonID_Weight/7TeV/2013FinalPaper_PhotonID_Barrel_BDT_TrainRangePT15_7TeV.weights.xml
/home/veverka/cms/cmssw/032/CMSSW_5_3_14/src/MitPhysics/data/2013FinalPaper_PhotonID_Weight/7TeV/2013FinalPaper_PhotonID_Endcap_BDT_TrainRangePT15_7TeV.weights.xml
/home/veverka/cms/cmssw/032/CMSSW_5_3_14/src/MitPhysics/data/2013FinalPaper_PhotonID_Weight/8TeV/2013FinalPaper_PhotonID_Barrel_BDT_TrainRangePT15_8TeV.weights.xml
/home/veverka/cms/cmssw/032/CMSSW_5_3_14/src/MitPhysics/data/2013FinalPaper_PhotonID_Weight/8TeV/2013FinalPaper_PhotonID_Endcap_BDT_TrainRangePT15_8TeV.weights.xml