devices v0.1.0

This is the initial release of the github.com/moby/sys/devices
module. The code is taken from the
github.com/opencontainers/runc/libcontainer/devices package as
of runc v1.4.0, with a few commits on top to adapt to the new
location.

The functionality here is not used by runc itself, but is used
by higher-level runtimes to generate device configurations for
runc. See issue 181 for more details.

Most of the git history is migrated, except for some of the
pre-2015 commits. Commit runc@8f97d39 moved libcontainer
into a subdirectory, meaning the libcontainer/devices glob is
missing commits before then, but this should be sufficient.