New interface proposal for schema definition

[hfaran]

Rather than using the awkward apid class variable...

from tornado_json import schema

@schema.validate
def post(self):
    """POST the required parameters to rule the world

    * `secret`: The secret to ruling the world 
    """
    __schemas__ = schema.Schema(
        input=input_schema,
        output=output_schema
    )
    __schemas__["input"]["example"] = ...
    __schemas__["output"]["example"] = ...

    # Do some cool stuff here
    # ...
    return world

That is:

• Schemas will be defined inside the relevant method
• The documentation will be provided in the docstring

[hfaran]

Use inspect.cleandoc to remove whitespace from documentation to preserve formatting for GFM.

[hfaran]

__schemas__ can instead be provided as a keyword-argument. Tornado should probably ignore it; however, can be stripped out if needed by modifying the method in BaseHandler.initialize

[hfaran]

Schemas can actually probably just be decorators, since the documentation is generated on app startup anyways.

@input_schema(schema=..., example=...)

[hfaran]

Resolved by #41