auroradns: Implement iterator for zones and records

[wido]

By implementing iterate_zones() and iterate_records() you can
iterate over zones and records returned by the API.

The list_zones() and list_records() methods simply talk to the
iteration functions and create a list of it and return that.

The test cases should still match since they call the list functions
and those call the iterators on their turn.

[tonybaloney]

thanks @wido it would be great to update the test case to validate that the responses are infact tuples or iterate the responses. the current case I think just checks the first response.
e.g.
assertEqual(tuple(generator_object), (1, 2, ...))

[wido]

@tonybaloney Thanks for the feedback! I expanded one test-case slightly, but the records were already iterated.

Or I might be missing your point here. But the list_records/zones calls call the iterate functions, so that tests it from beginning to end, right?

[tonybaloney]

cool, 👍 then. you need to make sure you make multiple assertions for a generator method, that was all I was suggesting.

[Kami]

Thanks for this change.

I know I am a bit late, but anyway. I removed the list_* methods from the driver since they are a bit redundant - they are already implemented on the base driver (52b037b).