[Hawkular-dev] docker clean up

[John Mazzitelli]

Just a little set of tricks that might be helpful to others.

If you want to clean up your docker:

* Delete all containers: docker ps -q -a | xargs docker rm
* Delete all images: docker rmi $(docker images --filter dangling=true)
* Another way of removing all images is: docker images -q | xargs docker rmi
* If images have dependent children, forced removal is via the -f flag: docker images -q | xargs docker rmi -f
* Delete untagged images: docker rmi $(docker images | grep "^<none>" | awk '{print $3}')