Add David Hoppner to author file.

AUTHORS

@@ -15,6 +15,7 @@ Didier Gazen <gazdi(at)aero.obs-mip.fr>
 Mark Grondona <mgrondona(at)llnl.gov>
 Takao Hatazaki <takao.hatazaki(at)hp.com>
 Matthieu Hautreux <matthieu.hautreux(at)cea.fr>
+David Hoppner <0xffea(at)googlemail.com>
 Christopher Holmes <cholmes(at)hp.com>
 Nathan Huff <nhuff(at)geekshanty.com>
 David Jackson <jacksond(at)clusterresources.com>