Wrap message receiver for minimum api exposure

Initializing a message receiver opens the socket and starts listening
right away rather than requiring a separate call to connect. The only
other publicly accessible method is to query the socket status.

// FREEBIE

js/libtextsecure.js

@@ -39469,6 +39469,7 @@ function generateKeys(count, progressCallback) {
         } else {
             throw new TypeError('MessageReceiver expected an EventTarget');
         }
+        this.connect();
     }
 
     MessageReceiver.prototype = {
@@ -39624,8 +39625,16 @@ function generateKeys(count, progressCallback) {
         }
     };
 
-    textsecure.MessageReceiver = MessageReceiver;
+    textsecure.MessageReceiver = function (eventTarget) {
+        var messageReceiver = new MessageReceiver(eventTarget);
+        this.getStatus = function() {
+            return messageReceiver.getStatus();
+        }
+    }
 
+    textsecure.MessageReceiver.prototype = {
+        constructor: textsecure.MessageReceiver
+    };
 
 }());