Don't pass options to subscribe
Use original topic when finding qos of client
Cope with close event from client
Fixed test which was failing due to publishing after disconnect
Added test to show why this change in mosca:

-    var qos = Math.min((options && options.qos) || 0,
-                       client.subscriptions[topic]);
+    var qos = Math.min(
+            (options && options.qos) || 0,
+            client.subscriptions[
+                    (sub_topic && sub_topic.replace("*", "#")) || topic] || 0);

and therefore this change in ascoltatori:

+      handler = null,
+      cb = null;
+
+    cb = function (pub_topic, payload, options) {
+      callback(pub_topic, payload, options, topic);
+    };

are necessary. Otherwise, subscriptions qos levels aren't retrieved correctly
(get from the topic in the message rather than the subscribed topic).
subscribe with closure around forward so we know the original topic
Merge pull request #28 from davedoesdev/pass_options_to_backend

Don't pass options to subscribe