Nexus Kenai Realm Plugin.

While this realm is not shipped with any of distros
it's OSS plugin for Nexus, hence it built with Nexus OSS.
Moved in Kenai Realm into Nexus Kenai plugin
Codified the testing wiki.

This is simple IT that actually drives nexus-kenai-plugin
(with a mock Kenai server) and verifies logging in and corresponding
role mapping works with Kenai realm.
Cleanup.

Javadoc, since tags, imports...
Missing XML license header
Making Kenai AuthAPI Behaviour more correct.

By specs, it should respond to POST only.
NXCM-5206: NEXUS-5585: Bumped HC4 version to 4.2.5

For NXCM-5206 it contains fix for following issue:
https://issues.apache.org/jira/browse/HTTPCLIENT-1340

For NEXUS-5585: it _might_ fix some NTLM/proxy/407 related issues
fixed in 4.2.3 release of HC4
[NEXUS-5672] Move images overridden by the different bundles back to webapp
- attempt to fix problems with configuration of windows ITs due to yammer metrics changes to jetty.xml  in 010d992c82d2e7567b2625af8d7b4941d272cb4f
Add custom InstrumentedSelectChannelConnector impl which sets up metrics on doStart() instead of CTOR so that configuration of the connector can be same as other standard connector impls.
add nexus-bootstrap to shared bullshit... fuck you nexus
more jetty.xml replacement junk... AAAAAH SUCH A CLUSTER FUCK