Tal 255 token scope verification

* the node client now caches scoped tokens as `token@scope` in redis
* modified gruntfile so that tests have a default timeout of 10 seconds
* added unit tests to assert the behaviour of the validateToken method
* added a utils file which contains a getAuthToken utility for the tests
* utils file also contains methods for returning stubRequest and
  stubResponse objects, this is because we use the node client as
  express middleware, that accepts req and res, these need to be honored
  but also provide a way to assert whats happened