Add a joint ISC/Nominum copyright statement.

util/COPYRIGHT.NOM

+Portions Copyright (C) @YEARS@  Internet Software Consortium.
+Portions Copyright (C) @YEARS@  Nominum, Inc.
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM AND
+NOMINUM DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT
+SHALL INTERNET SOFTWARE CONSORTIUM OR NOMINUM BE LIABLE FOR ANY
+SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.