Add OomScoreAdj to configure container oom killer preferences

libcontainer v0.0.4 introduces setting `/proc/self/oom_score_adj` to
better tune oom killing preferences for container process. This patch
simply integrates OomScoreAdj libcontainer's config option and adjust
the cli with this new option.

Signed-off-by: Antonio Murdaca <amurdaca@redhat.com>
Signed-off-by: Antonio Murdaca <runcom@redhat.com>

docs/reference/commandline/create.md

@@ -58,6 +58,7 @@ Creates a new container.
       --name=""                     Assign a name to the container
       --net="default"               Set the Network mode for the container
       --oom-kill-disable=false      Whether to disable OOM Killer for the container or not
+      --oom-score-adj=0             Tune the host's OOM preferences for containers (accepts -1000 to 1000)
       -P, --publish-all=false       Publish all exposed ports to random ports
       -p, --publish=[]              Publish a container's port(s) to the host
       --pid=""                      PID namespace to use

docs/reference/commandline/run.md

@@ -62,6 +62,7 @@ parent = "smn_cli"
                                     'host': use the host network stack inside the container
                                     'NETWORK': connects the container to user-created network using `docker network create` command
       --oom-kill-disable=false      Whether to disable OOM Killer for the container or not
+      --oom-score-adj=0             Tune the host's OOM preferences for containers (accepts -1000 to 1000)
       -P, --publish-all=false       Publish all exposed ports to random ports
       -p, --publish=[]              Publish a container's port(s) to the host
       --pid=""                      PID namespace to use