to setup controller using block.

I implemented @colinta 's idea which was discussed below link.
https://groups.google.com/d/msg/rubymotion/M9T6LybaEUs/AWip_Vwy5_4J

When you want to setup UIViewController, you can setup it in a block of tests method.

# Example
```Ruby
 describe MyViewController do

    tests MyViewController do |controller|
      # you can set data to the controller here
      controller.my_data = "foo"
    end

    .
    .
  end
```