Add support for the App Engine Admin API

[JustinBeckwith]

We have an Admin API (service management) for App Engine here:
https://cloud.google.com/appengine/docs/admin-api/reference/rest/

It's a pretty basic CRUD / REST style API, but it would be great to have wrappers that make it easier to use.

[mziccard]

Thanks for sharing this. Any idea when a v1 will be available?

[JustinBeckwith]

It's coming in the next 2-3 months. I think it's mostly going to be backwards compatible.

[garrettjonesgoogle]

Requests for supporting new clients are tracked internally. I'm going to close out this issue.