Basic version of libcontainer API.

This version has mostly the behavior available today and the
functionality agreed upon in other PRs. Further changes will be sent as
smaller PRs for discussion.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Update api proposal

Move concepts into specific files for easy management
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: vmarmol)
Add a cleanup method to cgroup fs. This will help in building a
standalone cgroup test util. systemd does auto cleanup on empty, so
doesn't need an extra interface.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge pull request #74 from rjnagal/cgroup_testing

Add a cleanup method to cgroup fs. This will help in building a
Merge pull request #67 from vmarmol/api2

Basic version of libcontainer API.
Ignore stats that are not available

Closes #13

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Merge pull request #75 from vmarmol/fix-stats

Ignore stats that are not available
Adding Initialize() to create a new container.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Fix spelling

Docker-DCO-1.1-Signed-off-by: Lee Treveil <leetreveil@gmail.com> (github: leetreveil)
Rename package correctly so the binary is nsinit
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #78 from crosbymichael/rename-nsinit-main

Rename package correctly so the binary is nsinit
Merge pull request #76 from vmarmol/api-init

Adding Initialize() to create a new container.
Add a standalone test utility for cgroup package.
Although it has some overlap with nsinit utility, it is useful to test
cgroup functinality directly and try out new or internal features not
exposed through nsinit.

It still needs some work as I haven't added enough systemd support yet.
I also need to expose an enter method.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Cleanup checks for non-existent cgroup file to be concise.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Improved comment and names.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge pull request #80 from rjnagal/cgroup-cleanup

Change checks for non-existent cgroup file to a more concise form.
Allow caller to change the labels on a directory tree.

We want to add this to libcontainer so that we can change docker so that
when you volume mount into a labeled container, we want to allow the
administrator/user the ability to tell docker to fix the labels on the mount.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Merge pull request #77 from leetreveil/spelling

Fix spelling
Add Load method to factory

Also update Initialize to take a path to the container
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Replace ID with Path on the container
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)