Make __repr__ slightly more detailed and add a few missing ones.

This includes raw events (which didn't have any) and a few other
types that were missing them. Upon review some more useful fields were
added to the repr output which would be more useful during debugging.

discord/object.py

@@ -64,6 +64,9 @@ class Object(Hashable):
     def __init__(self, id):
         self.id = id
 
+    def __repr__(self):
+        return '<Object id=%r>' % self.id
+
     @property
     def created_at(self):
         """Returns the snowflake's creation time in UTC."""