[NEW] net/py-sshuttle: Full-featured VPN over an SSH tunnel

As far as I (the author) knows, sshuttle is the only program that solves
the following common case:

• Your client machine (or router) is Linux, FreeBSD, or MacOS.
• You have access to a remote network via ssh.
• You don't necessarily have admin access on the remote network.
• The remote network has no VPN, or only stupid/complex VPN protocols (IPsec, PPTP, etc). Or maybe you are the admin and you just got frustrated with the awful state of VPN tools.
• You don't want to create an ssh port forward for every single host/port on the remote network.
• You hate openssh's port forwarding because it's randomly slow and/or stupid.
• You can't use openssh's PermitTunnel feature because it's disabled by default on openssh servers; plus it does TCP-over-TCP, which has terrible performance

WWW: https://github.com/sshuttle/sshuttle

While I'm here, patch out pytest-runner from setup_requires and add it
to tests_require. It's a test dependency, and pytest upstream
shouldn't 'recommend' otherwise in its 'Usage:' docs.

[1] https://github.com/sshuttle/sshuttle/issues/115

Requested by: John Kozubik (rsync.net, Inc) via freebsd-jobs