Add User.getLastModifiedTime()

lib/models/user.js

@@ -29,6 +29,7 @@ function User(userId) {
         presence: null,
         profile: null
     };
+    this._updateModifiedTime();
 }
 utils.inherits(User, EventEmitter);
 
@@ -64,11 +65,23 @@ User.prototype.setPresenceEvent = function(event) {
     this.avatarUrl = event.getContent().avatar_url;
     this.lastActiveAgo = event.getContent().last_active_ago;
 
+    if (eventsToFire.length > 0) {
+        this._updateModifiedTime();
+    }
+
     for (var i = 0; i < eventsToFire.length; i++) {
         this.emit(eventsToFire[i], event, this);
     }
 };
 
+User.prototype._updateModifiedTime = function() {
+    this._modified = Date.now();
+};
+
+User.prototype.getLastModifiedTime = function() {
+    return this._modified;
+};
+
 /**
  * The User class.
  */