Apply the ECL License

Fixes #18

Author: ahankinson

LICENSE

@@ -0,0 +1,16 @@
+NOTICE: Copyright (c) 2017 by the Music Encoding Initiative (MEI) Council.
+
+Licensed under the Educational Community 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 https://opensource.org/licenses/ECL-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.
+
+This is a derivative work based on earlier versions of the schema © 2001-2006 Perry Roland
+and the Rector and Visitors of the University of Virginia; licensed under the Educational
+Community License version 1.0.
+
+CONTACT: info@music-encoding.org