CORSMiddleware doesn't check for sinks

[guanzo]

The cors middleware only checks for registered routes, but not for registered sinks.
https://github.com/timothycrosley/hug/blob/22e7de475d4a150abe356b175a6d8aa14b8418bf/hug/middleware.py#L141-L147

Here's a code sample:

api = hug.API(__name__)
api.http.add_middleware(CORSMiddleware(api))
router = hug.http(api=api)

@router.get('/test')
def test():
    pass

@hug.sink('/sinktest', api=api)
def foo(path):
    pass

Visiting /test obviously works, but visiting /sinktest will trigger a KeyError at line 145.

This seems like an oversight, a sink route should still have allowed methods.

Speaking of allowed methods, how do I specify which HTTP verbs a sink route should respond to? I have a requires=token_authentication argument on my sink route, causing the router to check for an authorization header on the OPTIONS request, which is incorrect. OPTIONS requests don't send any authentication details. If I can specify that my sink route only accepts GET, then it won't trigger the token_authentication function.