Add ability for spec "stubs"

[OldhamMade]

There's as of yet no way to create an "empty" spec that doesn't implicitly pass but also doesn't fail. For instance, since specloud is used for BDD, one may wish to create the specification for a whole project but not implement any of the methods. However, since all the tests must pass, one is unable to work iteratively to make a subset of the tests pass to implement individual features.

It would be useful to be able to create spec "stubs", so one can use specloud to "plan" the project and then iteratively implement features.

I would see this as doing the following:

class PlannedFeatureSpec(unittest.TestCase):
    def it_must_do_something_new(self):
        raise NotImplemented()

This then would show up as orange in the specloud output and be ignored so that if it were the only spec the suite would still pass.

Hope this makes sense!