Remove .npm cache from stackviz element

Don't leak cache files to final image.

Change-Id: I61d428d6c24eee76bfeda2a3c7c6311d401615b7
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

nodepool/elements/stackviz/cleanup.d/50-npm

@@ -0,0 +1,23 @@
+#!/bin/bash
+#
+# Copyright 2017 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+if [ ${DIB_DEBUG_TRACE:-1} -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+sudo rm -rf $TARGET_ROOT/root/.npm