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.
Enrich logging for a a flaky test in IndexOperationIT which will help to show the real cause of tx commit failures
Improving unmanaged extensions docs

* Example of streaming back the response
* Example of using a single ExecutionEngine
* Reordering the explanation of the basic example
Remove extra PlanDescription API from javacompact
Improvements to unmanged extention and neo4j-harness docs.
Merge pull request #3626 from davidegrohmann/2.2-add-ids-to-json-plan-desc

Remove extra PlanDescription API from javacompact
Merge pull request #3623 from S124568/cluster-formation-fix

Enrich logging for a flaky test to show the real cause of tx commit failures
Merge pull request #3597 from jimwebber/2.1-maint

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

Improving docs for unmanaged extensions and neo4j-harness
Merge remote-tracking branch 'upstream/2.1-maint'

Conflicts:
	community/server-examples/LICENSES.txt
	community/server-examples/NOTICE.txt
	community/server-examples/src/docs/dev/server-unmanaged-extensions.asciidoc
Update unmanged extension docs for 2.2.