Update _down: now more Docker cache management

Performance issue.

Author: Julien Neuhart

_bin/_down

@@ -17,14 +17,6 @@ down()
     fi;
 }
 
-cache()
-{
-    docker rm $(docker ps -q -f status=exited) >/dev/null;
-    docker rmi $(docker images -q -f dangling=true) >/dev/null
-    docker volume rm $(docker volume ls -qf dangling=true) >/dev/null;
-}
-
 down;
-cache;
 
-exit 0;
+exit 0;