This patch adds SELinux labeling support.

docker will run the process(es) within the container with an SELinux label and will label
all of  the content within the container with mount label.  Any temporary file systems
created within the container need to be mounted with the same mount label.

The user can override the process label by specifying

-Z With a string of space separated options.

-Z "user=unconfined_u role=unconfined_r type=unconfined_t level=s0"

Would cause the process label to run with unconfined_u:unconfined_r:unconfined_t:s0"

By default the processes will run execute within the container as svirt_lxc_net_t.
All of the content in the container as svirt_sandbox_file_t.

The process mcs level is based of the PID of the docker process that is creating the container.

If you run the container in --priv mode, the labeling will be disabled.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Ignore *.patch and *~ in git

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Remount /var/lib/docker as --private to fix scaling issue

If an admin mounts all file systems as -rshared (Default on RHEL and Fedora)
we see a scaling problem as the number of container increase.

Basically every new container needs to have it new mounts in /var/lib/docker
shared to all other containers, this ends up with us only able to scale to
around 100 containers, before the system slows down.

By simply bind mounting /var/lib/docker on its and then setting it private,
the scaling issue goes away.
Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Setup LISTEN_PID correctly for socket activations
Inform processes in the container that they are running in a docker container

Init systems like systemd use this to determine they are running in a non
privleged environment.