add Eclipse Foundation specific Apache 2.0 license header (#178)

Author: gdams

assets/header-templates/Apache-2.0-EF.txt

@@ -0,0 +1,7 @@
+Copyright (c) [year] [owner]
+
+This program and the accompanying materials are made
+available under the terms of the Apache Software License 2.0
+which is available at https://www.apache.org/licenses/LICENSE-2.0.
+
+SPDX-License-Identifier: Apache-2.0