Decouple chat from core and add chat rest api (#25)

* Decouple the chat package from the core

* Add rest api endpoints for the chat aspect

models/chatListener.go

@@ -0,0 +1,8 @@
+package models
+
+//ChatListener represents the listener for the chat server
+type ChatListener interface {
+	ClientAdded(clientID string)
+	ClientRemoved(clientID string)
+	MessageSent(message ChatMessage)
+}