Move from ak5 to ak4 jets in the metUncertainty tool

The AK5 jets has been switched to ak4 jets inthe MET uncertainty tool called in the miniAOD configuration for consistency with the other jets in the CMSSW_7_0_X release

Two files modified with the following change :
-miniAOD configuration changed
-recoPFJet sequence with now the build of ak4Jets

No (not yet), MET corrections with CHS jets have never been tried.