legal: address more EMO review comments

* Add copyright headers to XML and YAML files
    * Add (tm) to the first mention of Eclipse MRAA in the README
    * Rename COPYING to LICENSE.md per the standard Eclipse requirement

Signed-off-by: Alex T <alext.mkrs@gmail.com>

.travis.yml

@@ -1,3 +1,11 @@
+# Copyright (c) 2015 Intel Corporation and others
+#
+# This program and the accompanying materials are made available under the terms
+# of the MIT license which is available at
+# https://projects.eclipse.org/license/mit-license-mit.
+#
+# SPDX-License-Identifier: MIT
+
 dist: trusty
 sudo: required