Update dockerCleanUpImages.sh

mawk does not understand '\s' notation.

Author: sebma

shl/dockerCleanUpImages.sh

@@ -3,4 +3,4 @@
 type sudo >/dev/null 2>&1 && [ $(id -u) != 0 ] && groups | egrep -wq "sudo|adm|admin|root|wheel" && sudo="sudo" || sudo=""
 groups | egrep -w docker && docker=docker || docker="$sudo docker"
 
-$docker image ls | awk '/^<none>\s+<none>/{printf" "$3}' | \xargs -rt $docker rmi
+$docker image ls | awk '/^<none>[[:space:]]+<none>/{printf" "$3}' | \xargs -rt $docker rmi