Add catch & finally methods to Transition

Add label parameter to the then method

lib/router/transition.js

@@ -126,11 +126,48 @@ Transition.prototype = {
     use in situations where you want to pass around a thennable,
     but not the Transition itself.
 
-    @param {Function} success
-    @param {Function} failure
+    @param {Function} onFulfilled
+    @param {Function} onRejected
+    @param {String} label optional string for labeling the promise.
+    Useful for tooling.
+    @return {Promise}
    */
-  then: function(success, failure) {
-    return this.promise.then(success, failure);
+  then: function(onFulfilled, onRejected, label) {
+    return this.promise.then(onFulfilled, onRejected, label);
+  },
+
+  /**
+    @public
+
+    Forwards to the internal `promise` property which you can
+    use in situations where you want to pass around a thennable,
+    but not the Transition itself.
+
+    @method catch
+    @param {Function} onRejection
+    @param {String} label optional string for labeling the promise.
+    Useful for tooling.
+    @return {Promise}
+   */
+  catch: function(onRejection, label) {
+    return this.promise.catch(onRejection, label);
+  },
+
+  /**
+    @public
+
+    Forwards to the internal `promise` property which you can
+    use in situations where you want to pass around a thennable,
+    but not the Transition itself.
+
+    @method finally
+    @param {Function} callback
+    @param {String} label optional string for labeling the promise.
+    Useful for tooling.
+    @return {Promise}
+   */
+  finally: function(callback, label) {
+    return this.promise.finally(callback, label);
   },
 
   /**