Add Vagrant configurations for multiple different systems to contrib

Vagrant can enable us to have pre-configured VM blueprints with Tor development environment that developers could easily instantiate on their local machines.

We should have Vagrantfiles for:

• Linux (at least Debian, maybe some more).
• FreeBSD
• OpenBSD
• NetBSD
• Windows 10 (stretch goal)
• Android-x86 (stretch goal)