Revert "simplify vagrant box"

Now that some tests only run on Linux it's nice to have Go and Git on there.

This reverts commit 989da03d9b659b03940ce2d3facc2b544608bc3e.
set up vagrant env for development
add more tests for isolation

* test IPC isolation by creating shared memory outside, and creating it again
  inside; the inner create will fail if not isolated, as it already exists

* test network isolation by making a new network inside and seeing that it is
  not created outside

* test mount space isolation by bind-mounting something inside and seeing that
  it doesn't show up in /proc/mounts outside

* test UTS isolation by changing the hostname inside and seeing that it's not
  changed outside