+++++++++++++++++++
Features:
- *Backwards-incompatible*: Don't prefix all routes in the spec with
``APPLICATION_ROOT``. If using OpenAPI v2, set ``APPLICATION_ROOT`` as
``basePath``. If using OpenAPI v3, the user should specify ``servers``
manually.
- *Backwards-incompatible*: In testing and debug modes, ``verify_check_etag``
not only logs a warning but also raises ``CheckEtagNotCalledError`` if
``check_etag`` is not called in a resource that needs it.