Update COPYING

Author: tuxmuck

COPYING

@@ -2,7 +2,7 @@
 		       Version 2, June 1991
 
  Copyright (C) 1989, 1991 Free Software Foundation, Inc.
-                      59 Temple Place, Suite 330, Boston, MA 02111 USA
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.