Add --security-opts options to allow user to customize container labels.

security-opts will allow you to customise the way that a labeling system like
SELinux will run on a container.

    --security-opt="user:USER"  : Set the label user for the container
    --security-opt="role:ROLE"  : Set the label role for the container
    --security-opt="type:TYPE"  : Set the label type for the container
    --security-opt="level:LEVEL"  : Set the label level for the container
    --security-opt="disabled"  : Turn off label confinement for the container

Since we are passing a list of string options instead of a space separated
string of options, I will change function calls to use InitLabels instead of
GenLabels.  Genlabels interface is Depracated.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Need a comma after "containers" or maybe after "override". I can't quite tell where that dependent clause is supposed to end. Maybe there's a missing word or something too, the independent clause doesn't quite make sense.