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)