Guideline compliance doc

It was suggested at the OpenStack Summit in Austin [1] that there could be a project tag(s) for API WG guideline compliance. Exactly what those tags would be is an open question but one that is certain is that they would have to be based on hard criteria.

The best form for that hard criteria are tests that prove a project conforms to a particular guideline. We already have a tool capable of employing such tests known as Gabbi.

To clarify the expectations of projects to meet these tests, we need a guideline compliance document. This document would

* bring together all of the guidelines to be tested in a checklist fashion
* recommend how to implement the test in Gabbi
* detail the project tag(s) the project receives as a result of their efforts

Let's start small. This document should begin with exactly one guideline and one Gabbi recommendation. We likely won't know what the project tag(s) look like until the idea has been kicked around a bit.

[1] https://etherpad.openstack.org/p/austin-api-wg-session-plans
[2] http://gabbi.readthedocs.io/en/latest/