Xd-docker

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* Add container_upload() method.
* Add commit() method.

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* Add container_remove() method.
* Add container_start() method.
* Add container_wait() method.
* Add container_stop() method.
* Add container_restart() method.
* Add container_kill() method.
* Allow private registry image names.
* Fixed handling of linked containers in containers().
* Support DOCKER_HOST environment variable.
* Add shell script to do manual testing.

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First development release