container-status

Currently , we don't have any fields to record the current status of a container. For example, when we create a container, we should record container status to success or fail.

And I think we should have at least two types of status like instances in nova:

1. status : indicate whether the container can be used or not.
    possible status:
    1) ACTIVE
    2) ERROR

2. Power state: When container is ACTIVE, this field indicate the power state of container
    possible state:
    1) Running
    2) Stopped
    3) Paused