Add JsonWritingTimeoutPoolOutputModule.

[dmitrijus]

This module adds two additional features (needed for the event display)
to the TimeoutPoolOutputModule:

1. file names now follow the DAQ/online convention (files are named
   run0001111_lumi0000_streamLabel_hostname.root);
2. for every file written (and after the file is closed), the json file
   containing some metadata is produced. This file signals DAQ
   services to start merging/distribution of the .root file.

[cmsbuild]

A new Pull Request was created by @dmitrijus (Dmitrijus) for CMSSW_7_2_X.

Add JsonWritingTimeoutPoolOutputModule.

It involves the following packages:

DQMServices/Components
DQMServices/StreamerIO
IOPool/Output

@Dr15Jones, @danduggan, @cmsbuild, @nclopezo, @deguio, @ktf can you please review it and eventually sign? Thanks.
@barvic, @wddgit, @wmtan this is something you requested to watch as well.
You can sign-off by replying to this message having '+1' in the first line of your reply.
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@nclopezo you are the release manager for this.
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[danduggan]

+1
We'd like this one for MWGR#9.

[Dr15Jones]

+1
Looks good to me.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_2_X IBs unless changes or unless it breaks tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[cmsbuild]

+1
Tested at: b2e6c5e
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6637/1186/summary.html

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_2_X IBs unless changes (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[ktf]

Merging this hoping it will not require a patch3.