CORS support in test server & helper

I'm not sure what is failing in tests, but I needed to debug the test servers by running `NODE_ENV=test coffee app.coffee` and `coffee test/api/server.coffee` then opening localhost:5000. This showed me an Ember Data "route loading" error being thrown because of a cross-domain restriction.

Since Zombie is server-side and uses [request](https://github.com/mikeal/request) underneath it shouldn't be restricted by the cross-origin browser restriction. So that wasn't the problem.

Regardless this should be helpful if you need to debug integration tests, just run `cake test:servers` and see what your integration specs are looking at.

Unfortunately it seems like something else is happening, potentially at the Ember-data level. If it's any help client-side javascript console.logs should output to stdout (that's why you can see "Expecting API server on http://localhost:5001 ... Fetching status ...") but to get a full output you'll want to run zombie with `debug: true` or `DEBUG=true mocha`.