Prevent dynamic allocation of previously allocated ports

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
Better test error message

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
Be more explicit in finding next port to allocate

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
Add err checks for port allocator tests

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
docker load: add --input flag

for those that do not care to read from redirected stdin

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
docker load: doc clarification

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
docker load: added example of a multiple tag image

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Merge pull request #4628 from kippandrew/port-allocator

Fix port collision with dynamically allocated ports
Merge pull request #4840 from vbatts/vbatts-load_from_input

docker load: add --input flag
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)