More forward porting from CMSSW_7_2_X

While forward porting the following bits conflicted:

- `RecoTracker/DeDx/plugins/HLTDeDxFilter.cc`

```
<<<<<<< HEAD 
       //calculate relative trk isolation only if parameter maxRelTrkIsoDeltaRp3 is less than 0 
       if(maxRelTrkIsoDeltaRp3_ >= 0){ 
         auto ptCone = trackCollection[i].pt(); 
         for(unsigned int j=0; j<trackCollection.size(); j++){ 
         reco::TrackRef track2  = reco::TrackRef( trackCollectionHandle, j ); 
======= 
       //calculate relative trk isolation only if parameter maxRelTrkIsoDeltaRp3 is greater than 0 
       if(maxRelTrkIsoDeltaRp3_ >= 0){ 
         auto ptCone = trackCollection[i].pt(); 
         for(unsigned int j=0; j<trackCollection.size(); j++){ 
>>>>>>> cms-sw/CMSSW_7_2_X 
```

In this case I picked up the 72X version since the commend is actually correct there.

- `Configuration/PyReleaseValidation/python/relval_steps.py`:

```
++<<<<<<< HEAD
 +steps['RECOHI']=merge([hiDefaults,{'-s':'RAW2DIGI,L1Reco,RECO,VALIDATION,DQM'},step3Defaults])
 +
++=======
+ steps['RECOHI']=merge([hiDefaults,{'-s':'RAW2DIGI,L1Reco,RECO,VALIDATION,DQM'},step3Up2015Defaults])
+ #wmsplit['RECOHI']=5
++>>>>>>> cms-sw/CMSSW_7_2_X
```

I picked up again the CMSSW_7_2_X version since that's what I was asked to do also in the past.