Adding BoostedJetMerger to PhysicsTools/PatUtils

[ferencek]

Backport of #3242

[cmsbuild]

A new Pull Request was created by @ferencek (Dinko Ferencek) for CMSSW_6_2_X_SLHC.

Adding BoostedJetMerger to PhysicsTools/PatUtils

It involves the following packages:

PhysicsTools/PatUtils

@nclopezo, @vadler, @cmsbuild, @Degano, @monttj can you please review it and eventually sign? Thanks.
@TaiSakuma, @nhanvtran this is something you requested to watch as well.
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@andersonjacob, @mark-grimes you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[vadler]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_6_2_X_SLHC IBs unless changes or unless it breaks tests. @andersonjacob, @mark-grimes can you please take care of it?

[mark-grimes]

merge

Doesn't check this change, but for the record:
Tests 10000, 10200, 10400, 11200, 11400, 12000, 12800, 13000, 13600 and 14600 pass all steps.
Tests 12200, 12400, 12600, 13800, 14000, 14200 and 14400 fail in step 2 with known errors.