Adds support for the Security Group extension to neutron

> In this case this tests that paging was successful.

Again, probably didn't express myself clearly here ;-) It looks like we are testing not just that the size of the collection is as expected, but that the order (well, we only test the first and last) is "as expected".

Are these intended to be ordered, then? And does the order need to match the order in which they are represented in the response, or is there some other ordering criterion? A comment in the test to clarify that would help, I think ;-)