Save outgoing attachments

js/models/threads.js

@@ -23,12 +23,17 @@ var Whisper = Whisper || {};
 
     sendMessage: function(message, attachments) {
       var timestamp = Date.now();
+      var base64_attachments = _.map(attachments, function(a) {
+        return ['data:', a.contentType, ';base64,', btoa(getString(a.data))].join('');
+      });
 
       this.messages().add({ type: 'outgoing',
                             body: message,
                             threadId: this.id,
+                            attachments: base64_attachments,
                             timestamp: timestamp }).save();
 
+
       this.save({ timestamp:   timestamp,
                   unreadCount: 0,
                   active:      true});