web: Display 'play' buttons next to images to run a container

These buttons don't do anything yet.

Got the column smaller by setting a fixed width on td.cell-buttons.
Not completetly happy with that, but perhaps there's not a better way.

Work on issue #301

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
web: Run images from the docker overview page

Bring up the run dialog by pressing the play button.

We no longer need to refresh the image information, as we have relevant
information being updated by the docker DOM code.

Work on fix for issue #301

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
web: Implement DockerClient.start() .stop() .restart()

Since we want to be able to call these from the overview page
in addition to the details page.

Part of issue #301

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
web: Start and stop containers with buttons on the overview page

Part of fix for issue #301

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>