add proper reverse proxy config for jenkins

jenkins throws a warning about a misconfigured reverse proxy, we need an
additional ProxyPassReverse stanza to correct it.
check if gears are already throttled. https://bugzilla.redhat.com/show_bug.cgi?id=1071167
Merge pull request #4797 from bparees/jenkins_rproxy

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Merge pull request #4854 from rajatchopra/master

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Merge pull request #4853 from danmcp/master

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