_inspector method can retry if it has no data.

* Model search logic broken out into its own method.
* Y.later calls _inspector if no model found.
* Retry limit in place.
* Drive by doc fix.
Cancel the timer on dispatch.
Tests.
Merge pull request #395 from jaycee/wait-for-inspector

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.