Docker: Add helpers for docker container operations

*  Updated documentation to include subtest.SubSubtestCaller
   class.  It was mistakenly not added previously.

*  Added minimal networking module with ContainerPort class.
   Follows very closely to the same pattern as images module.
   TODO: Add unittests
   TODO: Update Docs

*  Added minimal containers module also mirroring closely
   with the images pattern.  However there are quite a few
   more container attributes, only some are needed for
   creation, the rest are simply stuck onto the class.
   The DockerContainersBase class works similar to
   DockerImagesBase, minus the removal methods. Finally
   DockerContainersCLI and DockerContainers classes
   are nearly identical to the same from images.
   TODO: Add unittests
   TODO: Add removal methods
   TODO: Update Docs

*  Bumped revision number to 0.3.2

Signed-off-by: Chris Evich <cevich@redhat.com>