Feature/0.5.1/watson assistant integration

[uezo]

Attach and configure WatsonAssistantRequestProcessor to use ChatdollKit as a frontend channel of Watson Assistant.

Note:

• Make $end_conversation and set true to stop conversation loop.
• Experimental support for animation and face expression defined in Watson Assistant. Add iframe response following text response and define the name of animation and face expression as the iframe source.

{animation: "wave_hands", face: "smile"}