Summary:
Fixes T9762. Ref T10246.
**Disabling Bindings**: Previously, there was no formal way to disable bindings. The internal callers sometimes check some informal property on the binding, but this is a common need and deserves first-class support in the UI. Allow bindings to be disabled.
**Deleting Interfaces**: Previously, you could not delete interfaces. Now, you can delete unused interfaces.
Also some minor cleanup and slightly less mysterious documentation.
Test Plan: Disabled bindings and deleted interfaces.
Reviewers: chad
Reviewed By: chad
Subscribers: yelirekim
Maniphest Tasks: T9762, T10246
Differential Revision: https://secure.phabricator.com/D15345
