feat(ngRoute): expose parseRoute as public method

`$route.parseRoute` should be public, allowing you to determine which
route a given path will resolve to. This lets you store meta data in
your
routes config, and take action (e.g. cancel route) before the route
changes.

Example use case: before navigating, check if the route's feature is
feature-switched on or off. If off, cancel the route and display a
"feature disabled" popup.

Add a `feature` property to each route:

```js
$routeProvider.when('/profile',
  feature: 'profile',
  template: 'profile.html',
  controller: 'ProfileCtrl'
});
```

In a main controller, cancel routing and display popup when a route's
feature is disabled.

```js
$scope.$on('$locationChangeStart', function(e) {
  // determine the route the user is trying to navigate to
  var nextRoute = $route.parseRoute($location.path());
  // get the feature metadata from the route
  var nextFeature = nextRoute.$$route.feature;
  // check if the feature is set to disabled using an app-specific
  // service
  var status = AppFeatures.status(nextFeature);
  if (status === 'disabled'){
    // cancel the route
    e.preventDefault();
    // display popup
    $scope.showFeatureDisabledModal();
  }
});
```

Making `parseRoute` public gives your application a lot of flexibility
and control over routing.