Adding jd-au to mailmap

Author: bsipocz

.mailmap

@@ -28,6 +28,7 @@ Hans Moritz Guenter <moritz.guenther@gmx.de>
 Henrik Norman <honke.norman@gmail.com> <Honke.norman@gmail.com>
 Henrik Norman <honke.norman@gmail.com> <hnorma@kth.se>
 Jaladh Singhal <jaladhsinghal@gmail.com>
+James Dempsey <james.dempsey@csiro.au> <dem040@csiro.au>
 Javier Ballester <javier.ballester@ext.esa.int>
 Javier Duran <jduran@sciops.esa.int>
 Javier Duran <jduran@sciops.esa.int> <javier.duran@sciops.esa.int>