Adding my name to CONTRIBUTORS and AUTHORS

As Adam Langley mentioned, this should go in with
https://golang.org/cl/152141

R=rsc
CC=agl1
https://golang.org/cl/154138

AUTHORS

@@ -12,3 +12,4 @@ Abhinav Gupta <abhinav.g90@gmail.com>
 David Titarenco <david.titarenco@gmail.com>
 Google Inc.
 Kevin Ballard <kevin@sb.org>
+Môshe van der Sterre <moshevds@gmail.com>

CONTRIBUTORS

@@ -44,6 +44,7 @@ Kai Backman <kaib@golang.org>
 Ken Thompson <ken@golang.org>
 Kevin Ballard <kevin@sb.org>
 Larry Hosken <lahosken@golang.org>
+Môshe van der Sterre <moshevds@gmail.com>
 Nigel Tao <nigeltao@golang.org>
 Peter McKenzie <petermck@google.com>
 Phil Pennock <pdp@golang.org>