Add settings component and extra settings

[FabioRosado]

This PR adds a proper setting component which we can show when a user clicks the settings icon in the navbar. It also adds a few improvements and fixes for the websocket connector.

Here's what changed:

Websockets

• Allow users to set a token in the settings, this will be used when we do the initial request (this feature is currently commented out due to CORS issue)
  • Related Issue: Add possibility to configure CORS in routes opsdroid#1932
• Fix issue where the client would still be shown as connected when we get an OnClose event which wasn't clean. The client will now disconnect and show as disconnected if we get an OnCloseWithError event. This will be the initial step towards implementing reconnection logic
  • Related Issue: Implement websocket reconnect #26
• Add connect/disconnect button on the Navbar without the need to change host/port
• Send a stringified payload back to opsdroid so we can give opsdroid more information such as the name of the user that sent the message. This will stop opsdroid from replying with Hello None
  • Related PR: Small improvements to the websocket connector opsdroid#1931

User Settings

• Allow users to specify their username in the settings
• Send username when user sends message to opsdroid

Appearance

• Mostly just scaffolding, the components change the state but we aren't doing anything with it yet
  • Related issue Add logic to change appearance #30

Here's how the settings look like at the moment:

Closes #20