Add the copyright information in a dedicated file.

Change-Id: Ic8a416abdf6a408f899fe4caf82d32d849bbabcf

COPYRIGHT

+ETSI FORGE COPYRIGHT STATEMENT 
+
+Copyright (c) ETSI 2017. 
+
+This software is subject to copyrights owned by ETSI. Non-exclusive permission is hereby granted, free of charge, to copy, reproduce and amend this file under the following conditions: It is provided "as is", without warranty of any kind, expressed or implied. 
+
+ETSI shall never be liable for any claim, damages, or other liability arising from its use or inability of use. This permission does not apply to any documentation associated with this file for which ETSI keeps all rights reserved. The present copyright notice shall be included in all copies of whole or part of this software and shall not imply any sub-license right.