Add dashboard service

[Timothy-Gonzalez]

• Adds websocket support to core app
• Adds /dashboard service
  • ws /dashboard lets displays connect to the api
    • We ping these displays periodically for metadata and to verify they are alive
    • If displays miss pings for enough time, we time out and disconnect them
  • GET /dashboard returns the data for those connected displays
  • POST /dashboard/identify and POST /dashboard/identify/:id send a identify message to all or a specific display
  • POST /dashboard/reload and POST /dashboard/reload/:id send a reload message to all or a specific display
  • POST /dashboard/message and POST /dashboard/message/:id send a message to all or a specific display
• Add test websocket with promise hooks
• Add tests - we use port 4000 for the websocket server, in the future we might find a better solution to allow parallel testing