This patch serves as a trail blazer for Neutron API consolidation. It
introduces the following:
* It provides the API definitions to be used by a Neutron Stadium project.
* It introduces some testing scaffolding to validate the correctness of
an API definition and coverage for the extension.
* It provides the API reference documentation for the extension.
More patches will follow up to consolidate the rest of the Neutron APIs and
will use this as an example/template on how to approach the consolidation
effort.
Change-Id: Ie620a6fc21916ab34a19632c7fb9456b2c7c43b1
4da199808f