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
NX-156: fix REST-related split packages
NX-156: fix indexer-related split packages (excludes generated model classes)
Merge pull request #311 from sonatype/401-error-page

RFC: 403 error page
Merge pull request #314 from sonatype/NX-156-refactor-split-packages

REVIEW: NX-156: refactor split packages
Merge remote-tracking branch 'origin/master' into NEXUS-6220-conn-reuse
NEXUS-6220: Ask do we need connection reuse.

Before it was always "no". But, there are cases where
connection-reuse is needed, according to remote storage context
configuration.