license: clarify project contributors

The Hyades project would not be possible without our variety of
different contributors. This fixes the LICENSE file to no longer
incorrectly list me as the only contributor.

LICENSE

@@ -1,6 +1,14 @@
 MIT License
 
-Copyright (c) 2017 Cel Skeggs
+Copyright (c) 2017-2018 Cel Skeggs
+Copyright (c) 2017-2018 Mark Theng
+Copyright (c) 2017-2018 ikdc
+Copyright (c) 2018 Eleftherios Lef Ioannidis
+Copyright (c) 2018 David Sargent
+Copyright (c) 2017 Anders Kaseorg
+Copyright (c) 2017 Matthew Ince
+Copyright (c) 2017 Faye Dukhovni
+Copyright (c) 2017 Tony Wang
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal