LumiInfo classes for Run 2 luminosity information

[plujan]

This contains the new LumiInfo, LumiInfoRunHeader, and BeamCurrentInfo classes which will be used to store the Run2 lumi information. This is an update of PR #5314 which fixes the issues raised there. LumiInfoRunHeader now uses std::bitset to store the filling scheme information, and the beam intensities are now stored in 16 bits. This uses libminifloat, which is currently in DataFormats/PatCandidates -- it might be useful to move it to some central location.

[cmsbuild]

A new Pull Request was created by @plujan for CMSSW_7_3_X.

LumiInfo classes for Run 2 luminosity information

It involves the following packages:

DataFormats/Luminosity

@cmsbuild, @nclopezo, @StoyanStoynev, @slava77 can you please review it and eventually sign? Thanks.
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@nclopezo, @ktf you are the release manager for this.
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[cmsbuild]

+1
Tested at: 4fd7a98
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6204/644/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6204/644/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6204/680/summary.html

[StoyanStoynev]

+1
Tested 428a375 on top CMSSW_7_3_X_2014-11-04-0200 . No diffs in shortm matrix tests and none expected. This PR just introduces the initial version of the new lumi data format. May get small modifications while developing the rest of the code (in next days/weeks).

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_3_X IBs unless changes (tests are also fine). This pull request will be automatically merged.