supports folders with specs in them
Allow tested controllers to be embedded in standard containers

When declaring the controller under test, standard iOS container controllers
can now be stipulated through keyword options:

1. :navigation (UINavigationController)
2. :tab        (UITabBarController)
3. :present    (-presentViewController:animated:completion:)

Example:

    tests HamsterdamController, navigation: true

The use of container controllers is concatenative. For example, if both
:navigation and :tab are specified, the controller under test will be first
embedded in a navigation controller, and the navigation controller will be
embedded in a tab controller.

In the tests, #controller continues refers to the instance of the controller
under test even though it is no longer the window's root view controller. To
access a container controller, use one of UIViewControllers related controller
methods, such as #navigationController.
Namespace controller embedding options under :embed_in

Also, rename :present to :modal.
Use #include? to check :embed_in array
Merge branch 'spec_folders'
not sure this is the right place for this method, but it's handy, anyway
Merge branch 'spec_mode'