Convert CMake find-modules to BSD License

This adds copyright/license notification blocks CMake's find-modules.
Many of the modules had no notices at all.  Some had notices referring
to the BSD license already.  This commit normalizes existing notices and
adds missing notices.

Modules/FindUnixCommands.cmake

@@ -2,6 +2,19 @@
 # This module looks for some usual Unix commands.
 #
 
+#=============================================================================
+# Copyright 2001-2009 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distributed this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
 INCLUDE(FindCygwin)
 
 FIND_PROGRAM(BASH