Rebase of the CMSSW_7_1_THREADED_X branch on top of CMSSW_7_1_X

This was done via:

```
git checkout -b rebased-threaded origin/CMSSW_7_1_THREADED_X
git rebase -X theirs origin/CMSSW_7_1_X
```

and results in the same differences w.r.t. CMSSW_7_1_X that are there between CMSSW_7_1_X and CMSSW_7_1_THREADED_X.

Try to do that with CVS… :-)