Websocket refactor: Pull it out of the UI and support callbacks (#104)

* Websocket refactor: Pull it out of the UI and support listeners

* Changes required for Safari to be happy with modules

* Move to explicit ad-hoc callback registration

webroot/js/chat/socketMessageTypes.js

@@ -0,0 +1,11 @@
+/**
+ * These are the types of messages that we can handle with the websocket.
+ * Mostly used by `websocket.js` but if other components need to handle
+ * different types then it can import this file.
+ */
+export default {
+  CHAT: 'CHAT',
+  PING: 'PING',
+  NAME_CHANGE: 'NAME_CHANGE',
+  PONG: 'PONG'
+}