This commit adds a connection driver built on top of systemd-nspawn.
This is similar to the existing `chroot` driver, except that nspawn
offers a variety of additional services. For example, it takes care of
automatically mounting `/proc` and `/sys` inside the chroot environment,
which will make a variety of tools work correctly that would otherwise
fail.
You can take advantage of other system-nspawn features to perform more
complicated tasks. For example, on my x86_64 system I have a Raspberry
Pi disk image mounted on `/rpi`. I can't use `chroot` with this because
the binaries contained in the image are for the wrong architecture.
However, I can use the systemd-nspawn `--bind` option to automatically
insert the appropriate qemu-arm binary into the container using an
inventory file like this:
pi ansible_host=/rpi ansible_nspawn_extra_args='--bind /usr/bin/qemu-arm --bind /lib64'
See http://www.freedesktop.org/software/systemd/man/systemd-nspawn.html
for more information about systemd-nspawn itself.
