Add AUTHORS file; update LICENSE (#158)

AUTHORS

@@ -0,0 +1,43 @@
+# This is the official list of gorilla/sessions authors for copyright purposes.
+#
+# Please keep the list sorted.
+
+Ahmadreza Zibaei <ahmadrezazibaei@hotmail.com>
+Anton Lindström <lindztr@gmail.com>
+Brian Jones <mojobojo@gmail.com>
+Collin Stedman <kronion@users.noreply.github.com>
+Deniz Eren <dee.116@gmail.com>
+Dmitry Chestnykh <dmitry@codingrobots.com>
+Dustin Oprea <myselfasunder@gmail.com>
+Egon Elbre <egonelbre@gmail.com>
+enumappstore <appstore@enumapps.com>
+Geofrey Ernest <geofreyernest@live.com>
+Google LLC (https://opensource.google.com/)
+Jerry Saravia <SaraviaJ@gmail.com>
+Jonathan Gillham <jonathan.gillham@gamil.com>
+Justin Clift <justin@postgresql.org>
+Justin Hellings <justin.hellings@gmail.com>
+Kamil Kisiel <kamil@kamilkisiel.net>
+Keiji Yoshida <yoshida.keiji.84@gmail.com>
+kliron <kliron@gmail.com>
+Kshitij Saraogi <KshitijSaraogi@gmail.com>
+Lauris BH <lauris@nix.lv>
+Lukas Rist <glaslos@gmail.com>
+Mark Dain <ancarda@users.noreply.github.com>
+Matt Ho <matt.ho@gmail.com>
+Matt Silverlock <matt@eatsleeprepeat.net>
+Mattias Wadman <mattias.wadman@gmail.com>
+Michael Schuett <michaeljs1990@gmail.com>
+Michael Stapelberg <stapelberg@users.noreply.github.com>
+Mirco Zeiss <mirco.zeiss@gmail.com>
+moraes <rodrigo.moraes@gmail.com>
+nvcnvn <nguyen@open-vn.org>
+pappz <zoltan.pmail@gmail.com>
+Pontus Leitzler <leitzler@users.noreply.github.com>
+QuaSoft <info@quasoft.net>
+rcadena <robert.cadena@gmail.com>
+rodrigo moraes <rodrigo.moraes@gmail.com>
+Shawn Smith <shawnpsmith@gmail.com>
+Taylor Hurt <taylor.a.hurt@gmail.com>
+Tortuoise <sanyasinp@gmail.com>
+Vitor De Mario <vitordemario@gmail.com>

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2012 Rodrigo Moraes. All rights reserved.
+Copyright (c) 2012-2018 The Gorilla Authors. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are