Add Google+ Auto Backup.app latest version
user
```ruby
class GoogleAutoBackup < Cask
  url 'https://dl.google.com/dl/edgedl/picasa/gpautobackup_setup.dmg'
  homepage 'http://picasa.google.com/'
  version 'latest'
  no_checksum
  link 'Google+ Auto Backup.app'
end
```
assistant