Add Sonic Visualiser cask formula
user
```ruby
class SonicVisualiser < Cask
  url 'http://code.soundsoftware.ac.uk/attachments/download/907/Sonic%20Visualiser-2.3.dmg'
  homepage 'http://www.sonicvisualiser.org/'
  version '2.3'
  sha1 '024f6abc32f653162a04cbe7b0ed5dd4664c2611'
  link 'Sonic Visualiser.app'
end
```
assistant