Support django-rest-swagger style YAML docstrings

[axnsan12]

See http://django-rest-swagger.readthedocs.io/en/stable-0.3.x/yaml.html

Sometimes it can be easier to specify overrides in docstrings rather than code - for example, complex Schema, Parameter or Response objects. It could be worth looking into also being able to supply swagger_auto_schema overrides as YAML in view docstrings.

[Opa-]

This would be cool to handle extra headers parameters type 😃