Update CREDITS file

Change-Id: Ib1bbd3657b67d3f8de2806df6b887987eefb8994
Reviewed-on: http://review.couchbase.org/26107
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>