goprotobuf: Add Jeff Hodges to CONTRIBUTORS (individual CLA).

R=nigeltao, bradfitz
CC=golang-dev, jeff
http://codereview.appspot.com/6851106

CONTRIBUTORS

@@ -8,6 +8,7 @@
 
 Dave Cheney <dave@cheney.net>
 David Symonds <dsymonds@golang.org>
+Jeff Hodges <jeff@somethingsimilar.com>
 Jonathan Hseu <jhseu@google.com>
 Ken Thompson <ken@golang.org>
 Mikkel Krautz <mikkel@krautz.dk> <krautz@gmail.com>