Qg small updates

[tomcornelis]

These are a couple of small finalizing updates, following up to two bigger pull requests #7057 and #6931

• Change the product names of QGTagger.cc from axis2Likelihood, ptDLikelihood and multLikelihood to simply axis2, ptD and mult, because the former could be confusing
• Skip (very rare) jets with 2 or less particles (we need to have at least 3 particles to calculate a non-zero axis2).
• Provide the cfi fragment with default fragments, as was requested. Also "cmsRun jettoolbox_cfg.py" will work perfectly once I have the payloads uploaded to the database.

[cmsbuild]

A new Pull Request was created by @UAEDF-tomc (Tom Cornelis) for CMSSW_7_4_X.

Qg small updates

It involves the following packages:

RecoJets/JetProducers

@cmsbuild, @cvuosalo, @nclopezo, @slava77 can you please review it and eventually sign? Thanks.
@rappoccio, @ahinzmann, @TaiSakuma, @yslai, @nhanvtran, @schoef, @mariadalfonso this is something you requested to watch as well.
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[cvuosalo]

please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

+1
Tested at: 14922e9
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-7166/1870/summary.html

[cmsbuild]

+1
Tested at: 14922e9
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-7166/1871/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-7166/1870/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-7166/1871/summary.html

[cvuosalo]

+1

For #7166 14922e94f

Minor clean-up changes related to #7057 (the addition of a new weight for
likelihood variables).

Code changes are satisfactory.

Test of new functionality confirms that new likelihood variables are populated with reasonable values.

Jenkins tests CMSSW_7_4_X_2015-01-14-1400:
compilation, unit tests, matrix tests, static checks are all OK.

As expected, there are no differences compared to the baseline in the
following:

alternative-comparisons
(after stripping false positives like timer data)

and

validateJR

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs unless changes (tests are also fine). This pull request will be automatically merged.