Fix startup wizard.

MediaBrowser.Controller/Library/IUserManager.cs

@@ -52,6 +52,11 @@ namespace MediaBrowser.Controller.Library
         /// <value>The users ids.</value>
         IEnumerable<Guid> UsersIds { get; }
 
+        /// <summary>
+        /// Initializes the user manager and ensures that a user exists.
+        /// </summary>
+        void Initialize();
+
         /// <summary>
         /// Gets a user by Id.
         /// </summary>