Added CactusVPN Client

A software provided by CactusVPN to use their service.
I tested it and the only thing that seems to persist across installs/uninstalls are the -configuration files/login cookie/whatever it is they use for authentication- so you are still logged in when you reinstall the application.

Everything else is working:
- Install
- Uninstall

Problem I was facing was the incredibly stupid and file damaging download php they were using. I therefore hosted a downloaded pkg on my own server. SHA Hash is the same as the dl they provide(but doesn't work as a cask).