Provide feature to automatically update Lagoon Images

[Schnitzel]

docker image ls --format "{{.Repository}}:{{.Tag}}" | grep amazeeio/ | grep -v none | xargs -n1 docker pull | cat

[fubarhouse]

I've opened PR #21 to accommodate these changes.

I'm willing and happy to work with you to help here, so any feedback you can provide is appreciated.

edit:

Here's a sample for your convenience.