Retry inspector if it tries to load without service data.

Adds a Y.later based retry mechanism for the _inspector in cases where the service inspector should be opened but the services haven't had a chance to load from the environment yet.
This feels like it should be done at the top of the inspector dispatcher. I'm guessing it's done here however because there might be an active timer when the user navigates away? If this is the case could you add a comment to that effect so that future us know.