Issues in JS SDK

[chenkennt]

Use this issue to track the issues I found when using the SDK:

• Send message will stringify payload even it's plain text
  Send a message from server to client (e.g. use sendToAll), client will receive a message enclosed with quotes. The payload is treated as json and SDK does a JSON.stringify() over it even the payload is plain text.
• Client connection fails if onConnect returns nothing
  If onConnect handler returns nothing, client connection will fail. Need to return an empty object ({}) even no additional information is returned.
• User events are printed out in console by default
  SDK will print out all user events to console and seems it cannot be disabled.
• Incorrect connection request never returns response
  Use a http test tool like postman or curl to post a blank request to a event handler, SDK will throw exception as the request doesn't contain excepted headers, but the request never returns. The expected behavior should be returning 400.

[chenkennt]

• Url <event-handler-path>/ does not match <event-handler-path>
  Always get this error message when processing an incoming event
• Suggestion: provide a service client in event handler context

[chenkennt]

• WebPubSubServer.endpoint.clientNegotiate shouldn't require hubName
  Since it's already a parameter of WebPubSubServer constructor