Updated docker plugin to use Docker container names instead of hashes.

Since version 0.6.5 every Docker container has unique name.
http://blog.docker.io/2013/10/docker-0-6-5-links-container-naming-advanced-port-redirects-host-integration/

Currently the docker plugin provides auto-complete based on hashes.
This commit changes it to names(container hash is still visible).

Additionally plugin now shows all container not only running ones(useful for many Docker commands (start, rm))