Feature Request: Add get_domain_for functionality

[mcneely]

In https://docs.platform.sh/configuration/routes.html there's a function to pull routes by id. It would be nice if it was added to this package. That allows us to isolated platform related code as a dependency.

[Crell]

Hi Paul. We're actually nearly complete with a massive overhaul of all of our client libraries. You can see what the v2 is going to look like in PR #4. It's not quite done but should be out next week, I imagine. It includes a bunch of improvements, including the ability to get a route by its ID.