NEXUS-5118: Initial imple

Goal is to make "bundle packaging" (which is basically Jetty + Nexus WAR)
use same LogBack instance (as we had problems reported by users in 2.0).

Changes:
* jetty.xml - umarked "server level" logback as hidden to make it really shared
* extracted custom appender into new module nexus-logging-extras-appender that is put top level
* nexus-logging-extras got component implementation for EventTarget
* logback-events.xml changed to use new appender
* bundle assembly changed that exclude all logging relevant JARs from Nexus WAR as they are _provided_ on top level from now on

This is WIP, not yet functional.
NEXUS-5118: Adding exclusion for top level invluded JAR

Did not stir much water, but Tattletale chokes on this.
NEXUS-5118: Made a plexus component for EventTarget
NEXUS-5118: Making the Event Target a SISU component

But still no luck, probably due to this:
http://stackoverflow.com/questions/3567413/why-doesnt-a-missing-annotation-cause-a-classnotfoundexception-at-runtime
NEXUS-5118: Fixing the initial imple

The initial implementation was conceived okay, but
there was a problem with Injection happening as the class
loaded up had annotations thrown away by classloader.

Reason for that is that in bundle layout the appender
is on Jetty classloader level (parent of Nexus webapp)
and that CL does not have @Inject. Hence, the fix was to
introduce "special" case for injection when ForwaringAppender
was met, simply doing manual injection on it.
NEXUS-5118: Unrelated file on my local FS got into the commit by mistake.
NEXUS-5118: Added missing license
NEXUS-5241: Simple fix to not have some events stored to Timeline.

Simply adding extra checks: event to be stored relates to a path
that is:

* NOT maven repository metadata file (maven-metadata.xml)
* NOT maven artifact signature file (*.asc)
* NOT maven checksum file (*.sha1 or *.md5)

Note: this change makes Timeline Maven-support dependant. Today, this is
fine as Maven support happens to be in Core, but once moved out, this
solution will either require to have Timeline plugin depend on Maven plugin
(which is wrong) or removal of this change will be needed.
NEXUS-5241: UT covering change
o rewrite IT to be more reliable

The IT was running three tasks, then checking once whether one was sleeping and
then just waited for all tasks to be in the default state.

Now it's running three tasks, waits until one is sleeping (failing only
after 10s), then waits for completion of all tasks and asserts that they
actually ran after they were created.
NEXUS-5216: Fix.

The fix is actually done in dependency, change:
https://github.com/sonatype/nexus-archetype-common/commit/0f713327ed2481e01cf486e2f2f4cc8a7c4affaf
NEXUS-5216: More improvements to MAC plugin

* added log entry for NEXUS-5216 case, Nexus will nag you
if you fetch a catalog for a repository that is not indexable
(has no IndexingContext)
* Added repo URL as since initial implementation Nexus now has
means to build "repo URL"
* smaller improvements
Merge pull request #534 from sonatype/nxcm-1508-it-rewrite

o [NXCM-1508] Rewrite IT to be more reliable
o [NEXUS-5212] Fix typos
[NEXUS-5246] Use status 307 (temporary redirect) instead of 301 (permanent redact) to avoid browser caching

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge pull request #537 from sonatype/nexus-5246-permanent-redirect

[NEXUS-5246] Use status 307 (temporary redirect) instead of 301 (permanent redact) to avoid browser caching
o [NEXUS-5246] Fix ITs to expect temporary redirection
Merge pull request #530 from sonatype/nexus-5118

NEXUS-5118: Rationalizing logging in bundle
Merge pull request #536 from sonatype/nexus-5216

NEXUS-5216: Fix.
Merge pull request #531 from sonatype/nexus-5241-simple-fix

NEXUS-5241: Simple fix