NEXUS-6182: Make client multi-thread capable

Most notably, the connMgr used by HC4 for Client.
Also, some minor cleanups.
NX-164: rework uber classloader
Merge pull request #322 from sonatype/NEXUS-6182-mt-client

NEXUS-6182: Make client multi-thread capable
Bump to logback 1.1.0.
Removal of the hack, and programmatically install JUL level change listener.

To not have to much with existing logback XML configurations, but
have it "working out of the box".
Reshuffled installation location.

Made it happen early, before Joran sets
levels, to grab all the context events.
Merge pull request #323 from sonatype/NX-164-rework-uber-classloader

NX-164: rework uber classloader
Merge pull request #324 from sonatype/update-logback

Bump to logback 1.1.0.
Added missing m2e plugin exec mappings
Merge remote-tracking branch 'origin/master' into rapture