Add a cask-file for TestFlight 1.0_beta306
user
```ruby
class Testflight < Cask
  url 'https://d193ln56du8muy.cloudfront.net/desktop_app/1370377714/TestFlight-Desktop-1.0-Beta(306).zip'
  homepage 'http://testflightapp.com'
  version '1.0_beta306'
  sha1 '86180feb6e48c30501ec2a0428bb45f7b4fc3396'
  link 'TestFlight.app'
end
```
assistant