Fix on_close propogation + bump websocket-client

[wwwehr]

Satisfies https://github.com/watson-developer-cloud/python-sdk/issues/810

Also, the websocket client class sends messages to the on_close handler that do not match the signature that result in an error:

from callback <bound method SynthesizeListener.on_close of
 <ibm_watson.websocket.synthesize_listener.SynthesizeListener object at
 0x123456789>>: on_close() takes 2 positional arguments but 4 were given

This PR fixes this issue.

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[wwwehr]

@jeff-arn @kevinkowa @hsaylor

Hoping to get this reviewed and merged. I thought I followed the contributors notes - please advise if I need to do anything else!