refactor(mocks) : changed the implementations of expect any URL

Changed $httpBackend.expect any URL ( expect('GET') )  from undefined / null to * ( expect('GET', '*') )
I would go further and put an assertion in the MockHttpExpectation function that throws an explicit error if the url is undefined.

Then you don't need this line here at all because by the time you get here you are guaranteed that the URL is not undefined.

And also the user gets a clear error message if they failed to provide a URL.