Add a cask for Tiled.app
user
```ruby
class Tiled < Cask
  url 'http://downloads.sourceforge.net/project/tiled/tiled-qt/0.9.1/tiled-qt-0.9.1.dmg'
  homepage 'http://www.mapeditor.org/'
  version '0.9.1'
  sha1 'f7f30ec8761ffd7f293242287ff4d462e7ee17fb'
  link 'Tiled.app'
end
```
assistant