Add a real easy way to use VPN

Consistent with our project values, we should add a real easy way to use VPN.

Like, one click.

Ideally one that doesn't create logs and **needs no sign-up**, no no username and passwords.

https://leap.se/ lists some such providers:

* Riseup.net
* The Calyx Institute

These are using OpenVPN.

---

There is also

* https://github.com/Snawoot/hola-proxy/
* https://github.com/Snawoot/opera-proxy/

There are "Zero configuration" and "Simple and straightforward" (the project's description!), so match our philosophy exactly. But seem to be only for HTTP(S) and not system-wide.