Adding cases from the integration tests to the unit tests
Noting differences with the integration tests
Added some handy mockrunner classes

This way I don't have to build my own.
see: http://mockrunner.github.io/

They're explicitly added to the test scope, so they should not affect
dependencies of the actual artifacts. This should make it much easier to
test the filterchain without starting up all of repose.
Removed this test from here

For some reason, the filter's unit tests don't have the same effect as
the integration tests. So I have pulled these out to a slightly higher
level that lets us test the filter chain itself, so I can see all the
request/response pairs as it goes through the filter chain
This test fails properly, like the deproxy test

This goes up one level, providing the necessary mocks to get this
working. I'm sure there's plenty more refactoring that can be done to
improve this and reuse it on many branches, but it runs faster than
deproxy, since we don't have to actually start repose, as well it should
show me the entire filterChain, so I can know wtf is going on
For the MockServletRequest, we need to add each header individually
This test wasn't doing things right

This is why I got different results during the integration test.

The HttpServlet API is old, and kind of icky :(
Change the implementation of all this

Now it passes my more involved integration test, so lets see if it
passes the real integration test
Updated the integration test to include more things
Updated this deproxy test

The acceptance criteria for this is not very clear at all. I have
updated the backlog item with the behavior as I understood it to be
defined.

I took out/changed the tests that will not pass based on the behavior
described by Jorge Williams for this filter. There was still some
ambiguity around the order in which things are preferred.

I understood it to treat the configuration as a priority order. Higher
ordered items are preferred to lower ordered items, with the exception
of the "preferred" type which is always the most important one.