Added option to set gDebug from InitRootHandler's parameters

[Dr15Jones]

This change is useful when trying to determine what ROOT is actually doing.

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for CMSSW_7_0_X.

Added option to set gDebug from InitRootHandler's parameters

It involves the following packages:

FWCore/Services

@cmsbuild, @Degano, @Dr15Jones, @ktf, @nclopezo can you please review it and eventually sign? Thanks.
@wmtan this is something you requested to watch as well.
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@ktf you are the release manager for this.

[Dr15Jones]

+1
The default behavior is as before so there is no reason not to add this to 7_0_X.

[cmsbuild]

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

[cmsbuild]

+1
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-1966/1928/summary.html