Add additional tests for X-Forwarded-Host

Against Cypher REST response, and slash redirects
Fixed merge
Removed the integration tests pertaining to the correct use of X-Forward-* when redirecting from URIs that don't end in slash to ones that do*.

This is because there is some subtle interaction between Jetty and Jersey that screws this up. We've been through the Jetty code trying to see where this happens, but it's high cost for low value. Therefore when you don't correctly specify (say) /db/mabage/ and instead specify /db/manage then you will likely get incorrect URIs in the 302 response. the solution is not to use the wrong URI.

* This is a dumb decision by Jetty/Jersey. It is clear that http://example.com/foo/ and http://example.com/foo are not the same URI. Meh.
Merge pull request #3597 from jimwebber/2.1-maint

Backporting X-Forward-* bug fixes from master