Add prune script because docker takes up so much space

deploy/prune_docker.sh

@@ -0,0 +1,11 @@
+# Prune images and volumes
+# 
+# Docker tends to take a lot of space. This will remove dangling images and
+# volumes not used by at least container.
+# WARNING: You might not want to run this if you have stuff that are dangling
+# that you want to keep.
+#
+#!/bin/bash
+
+docker image prune -f
+docker volume prune -f