Add EPOS gen fragment for pPb relval

[mandrenguyen]

This generator fragment will be used for the pPb relval workflow (280) as agreed with @fabozzi
This workflow is currently still configured for Run 1, but will be updated shortly for Run 2.
The update to the configBuilder will come in a subsequent PR.
This PR will also be made into 80X.

[cmsbuild]

A new Pull Request was created by @mandrenguyen for CMSSW_8_1_X.

It involves the following packages:

Configuration/Generator

@cmsbuild, @govoni, @perrozzi, @thuer, @davidlange6 can you please review it and eventually sign? Thanks.
@ghellwig, @Martin-Grunewald this is something you requested to watch as well.
@slava77, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[perrozzi]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/15511/console

[cmsbuild]

+1
Tested at: f41cd4a
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16016/15511/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16016/15511/summary.html

[perrozzi]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_8_1_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @smuzaffar

[davidlange6]

+1