Add cask for ReadyTalk, an audio and web conferencing app.
user
```ruby
class Readytalk < Cask
  url 'https://core.readytalk.com/ql/bins/QuickLauncherInstall.dmg'
  homepage 'https://www.readytalk.com/'
  version 'latest'
  no_checksum
  link 'ReadyTalk Quick Launcher.app'
end
```
assistant