Simple 2.0 spec example

Here is a first example of the proposed 2.0 spec for comment
To be honest, I'm not really sure why it matters how it is done in JSON Schema. The JSON Schema, much like XSD, is a used to describe the format (and validation) of the target JSON. This doesn't mean we should aim to use the same terms used by JSON Schema as it doesn't really benefit us in any way (no way that I can see at least).

What I don't like about the current specification is that we sometimes use 'type' and sometimes '$ref' to address a model. The inconsistency makes it difficult to document and probably more difficult to automate.

It should be either 'type' or '$ref' throughout the spec. The advantage of using 'type' for everything is simplicity. Only one field is used to declare the type of a given object (whatever object it may be). The advantage of using '$ref' for models is the ability to have models with the same name as types and thus avoid ambiguity. 

Keep in mind we already don't use 'type' for primitives only as we have the type 'File'.