Testing with lua/atf-lua reviews

[Kyle Evans]

Hello!

I've just put up for review some work I've done to allow us to write
tests in lua, primarily intended to test the lua libs we're writing.
Please feel free to add yourself or drop in for some commentary:

- https://reviews.freebsd.org/D26928 - atf-lua(1)/atf-lua(3) itself
- https://reviews.freebsd.org/D26929 - Build glue for atf-lua
- https://reviews.freebsd.org/D26930 - atf.tests.mk infrastructure for
adding tests
- https://reviews.freebsd.org/D26931 - Build glue for atf-lua tests
- https://reviews.freebsd.org/D26932 - jail(3lua) tests, as a sample

Note that D26932 has an additional hard dependency on the libjail
bindings and some additions I've made to them, notably: D26080,
D26756, and D26927.

Thanks,

Kyle Evans