Integration test

These are the integration specs that are added:

- when accessing a protected url
	- redirects to GitHub for authentication
- when redirected back from GitHub
	- exchanges the code for an access token
	- and the returned state does not match the initial state
		- fails authentication
	- and GitHub rejects the code while exchanging it for an access token
		fails authentication
	- and code was exchanged for an access token
		- redirects back to the original path
- when not inside OAuth flow
	- does not recognize a seeming callback url as an actual callback
- when already authenticated
	- does not perform the OAuth flow again

The test coverage is now at 100% (SimpleCov reports less but that is because of ruby 1.8/1.9 branching)