Fix momentumTensor calculation

[sroecker]

Norm of momentumTensor should be initialized with zero

[cmsbuild]

A new Pull Request was created by @sroecker (Steffen Röcker) for CMSSW_7_1_X.

Fix momentumTensor calculation

It involves the following packages:

PhysicsTools/CandUtils

@nclopezo, @vadler, @cmsbuild, @Degano, @monttj can you please review it and eventually sign? Thanks.
You can sign-off by replying to this message having '+1' in the first line of your reply.
You can reject by replying to this message having '-1' in the first line of your reply.
@nclopezo, @ktf you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[nclopezo]

+1
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-%20sroecker:patch-1/1625/summary.html

[davidlange6]

@monttj - is this PR ok for you?

[monttj]

+1
apology for missing this one. It should be OK in AT.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_1_X IBs unless changes (tests are also fine). @nclopezo, @ktf can you please take care of it?