Bump the ruby version used to run the tests.
Merge pull request #76 from alphagov/bump_ruby

Bump the ruby version used to run the tests to 2.1.4.
Initial integration test harness.

Includes 404 test for router with no routes.
Hook new integration tests into `make test`
Initial basic routing tests.

This includes all the orchestration to create test backends, and get a
request through the router to them.
Port remaining backend selection tests to Go
Port redirect tests to Go.

This required switching from using http.Client to http.Transport to make
the http requests.  http.Client follows redirects by default, whereas
http.Transport operates at a lower level, and makes a single request.
This is what we want for these tests.
Port gone handler tests.

Also DRY up the route_helpers a bit.
Add helpers to capture router log output.
Port first part of proxy function tests.

These cover connections timeouts/issues etc.
Implement backend selection double slashes tests

Using gomega ghttp recorder.
Prevent HTTP request helpers setting a User-Agent.

The Go http library sets one by default, so we need to prevent this.
Port proxy header handling tests
Port remaining proxy function tests to Go
Initial performance test.

Basic test comparing router with direct requests.
Port remaining performance tests to Go