Tracking cluster charge cut and new iterative sequence

This is the promised pull to start bringing into the release the improvements in tracking in view of CSA14 and, in the longish run, for 2015 Data Taking. The main changes are:
* turn Cluster Charge Cut on, in its simplest form.
* swap iterations 3 and 1 to gain speed w/o giving up in eff or fake
* improved seeding for iteration 4, *MixedTriplets*.

Most of the changes have been presented and discussed during recent TrackingPOG meetings, e.g.: 
[Link in indico](https://indico.cern.ch/conferenceDisplay.py?confId=281373), mainly talks from KevinS, GiuseppeC and GiovanniZdv.

**The default tracking version is the improved one included in this pull request**.
A customise snippet has been added in release to be able to restore the _default tracking_ as of 2012. A typical example to re-activate the _old tracking_ via a cmsDriver command is:
```
cmsDriver.py stepXYZ --step RAW2DIGI,L1Reco,RECO,DQM --conditions auto:startup ..... --customise RecoTracker/Configuration/customiseForRunI.customiseForRunI
```

Expect differences in tracking, and possibly derived objects.