Support narrowing to a JSON Schema type in WADL

[RackerWilliams]

There was a promise to support this a couple of years ago don't want to lose it:

Okay here’s my recommendation:

Use the json schema namespace below...

<application xmlns="http://wadl.dev.java.net/2009/02”
                    xmlns:json="http://json-schema.org/schema#”>

then in the representation element use ref attribute in that namespace to put a JSON Pointer to the schema that should validate it:

<representation mediaType="application/json” json:ref="http://docs.openstack.org/api/open
stack-block-storage/v2/volume#post">

I’ll make sure to honor this at our end.