sendError to propagate 403 up to servlet container.
notes about why this is so fucking strange.
Add error.html web-resource to handle generic servlet error-page muck
Add dispatcher REQUEST and ERROR to guiceFilter so that error page references can be resolved.
Merge branch 'master' into 401-error-page

Conflicts:
	components/nexus-core/src/main/java/org/sonatype/nexus/security/filter/authc/NexusHttpAuthenticationFilter.java
NEXUS-6123: Special validation for site.xml added
NEXUS-6213: Added log line when lax XML validation is used

As basically this means XML was detected as invalid, but
lax XML validation overrides that to "neutral".
NEXUS-6213: Laxed site xml path matching.
NEXUS-6213: UT

With positive and negative tests.
Merge pull request #313 from sonatype/NEXUS-6213-site-xml

NEXUS-6213: Validation for Maven Site XML
Merge pull request #311 from sonatype/401-error-page

RFC: 403 error page
make feature menu stateful
make menu collapsible, since we have a title, no reason not to
drop resize handles, not needed when split: true
note where default feature selection is done
Merge branch 'master' into rapture