Add XCA - X Certificate and key management (latest) :fake user agent is required so sf.net will serve us the dmg instead of the source archive or Windows exe. Minimally, this seems to be dependent on the presence of the 'Intel OS X' string in the UA
user
```ruby
class Xca < Cask
  url 'http://sourceforge.net/projects/xca/files/latest/download',
    :user_agent => :fake
  homepage 'http://xca.sourceforge.net/'
  version 'latest'
  no_checksum
  link 'xca.app'
end
```
assistant