Support remote $ref-s

[ioggstream]

I expect

Remote $refs in parameters to be processed, eg

paths:
  /foo:
    parameters:
    - $ref: 'https://schema.example#/components/parameters/MyParam'

and in schema.example

components:
  parameters:
    MyParam:
      name: foo
      schema:
        type: string

Instead

I get NotImplementedError ;)

[koxudaxi]

@ioggstream
I have released a new version as 0.0.17
This version supports remote ref on parameters, requestBodies and responses #57