Manual merge 7_3_X into 7_3_ROOT6_X

Last Friday, I noticed that around October 22nd, the automatic merges from from CMSSW_7_3_X to CMSSW_7_3_ROOT6_X had merge conflicts and were not working. As you can see here:

https://cmssdt.cern.ch/SDT/html/showIB.html#CMSSW_7_3_ROOT6_X_2014-10-22-0200

I started from the branch CMSSW_7_3_ROOT6_X. I did <pre> git merge CMSSW_7_3_X </pre> and then I manually solved the conflicts with the help of @davidlt. 

I checked that https://github.com/cms-sw/cmssw/pull/5975 does no affect the files CondFormats/PhysicsToolsObjects/interface/MVAComputer.h or
CondFormats/PhysicsToolsObjects/src/MVAComputer.cc

If this is ok I can merge it and activate again the automatic merges which should work again.