prevent deletion if image is used by a running container
use utils.ParseRepositoryTag instead of strings.split in docker images
on docker start, do not cleanup if already running
fix nameserver regex.
modify test of GetNameserversAsCIDR for its regex change.
Add clarification of multiple "go test" calls in hack/make/*test
Merge pull request #2669 from tianon/clarify-test-calls

Add clarification of multiple "go test" calls in hack/make/*test
Merge pull request #2657 from dotcloud/fix_docker_images_output

use utils.ParseRepositoryTag instead of strings.split in docker images
Merge pull request #2614 from dotcloud/prevent_delete_image_running_container

Runtime: prevent deletion if image is used by a running container
Merge pull request #2662 from dotcloud/do_not_cleanup_start_if_running

on docker start, do not cleanup if already running
Merge pull request #2663 from viirya/fix_nameserver_regex

Fix nameserver regex