Create a filter for dealing with X-Forwarded-*.

Handles X-Forwarded-Host and X-Forwarded-Proto. Moved the handler code out of the OutputFormatProvider into a jetty filter much further down the stack. This should enable all of the Neo4j server resources (including / and /db/manage) to be addressed via an external hostname and other URI scheme.
Merge 2.0-maint into 2.1-maint