Add Cask for TileMill 0.10.1
user
```ruby
class Tilemill < Cask
  url 'http://tilemill.s3.amazonaws.com/latest/TileMill-0.10.1.zip'
  homepage 'http://www.mapbox.com/tilemill/'
  version '0.10.1'
  sha1 '5ea8ad1fc4153e98f37db20cc4ddbf8490e4e942'
  link 'TileMill.app'
end
```
assistant