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.
Make default CostEvaluator work with arbitrary numeric types
Merge pull request #3522 from jexp/2.1-maint

Make default CostEvaluator work with arbitrary numeric types
Improving unmanaged extensions docs

* Example of streaming back the response
* Example of using a single ExecutionEngine
* Reordering the explanation of the basic example
Improvements to unmanged extention and neo4j-harness docs.
Merge pull request #3597 from jimwebber/2.1-maint

Backporting X-Forward-* bug fixes from master
Merge pull request #3625 from nawroth/2.1-unex-docs

Improving docs for unmanaged extensions and neo4j-harness
Fixed typo in documentation.

Theere -> There.
Remove a file accidentally committed in June
Errors in Bootstrapper.start are logged to System.out if logging failed to initialize
Merge pull request #3634 from lutovich/2.1-npe-in-bootstrapper-catch-block

Null-safe logging in Bootstrapper
Unknown relationship types in a dense node should not cause relationship loading
Reserved rel-type records are marked not inUse during id generator rebuid
Merge pull request #3643 from lutovich/2.1-remove-reserved-rel-type-records

Reserved rel-type records are removed during IdGenerator rebuild