Test coverage bump

Bumping test coverage mainly for networking, but other services are affected too. Acceptance tests have been slightly reworked, and common Neutron code added for the new URL path system.
I've actually been thinking about enhancing `LinkedPageBase` to handle different styles of embedded links, notably including these "search for rel = 'next' in a collection of objects" style. Ideally you shouldn't have to override `NextPageURL` at all.

This is certainly a big improvement, though.