Update COPYING
Updated year
The MIT License (MIT)
-Copyright (c) 2009-2017 The Bitcoin Core developers
-Copyright (c) 2017 The Raven Core developers
-Copyright (c) 2009-2017 Raven Developers
+Copyright (c) 2009-2018 The Bitcoin Core developers
+Copyright (c) 2018 The Raven Core developers
+Copyright (c) 2009-2018 Raven Developers
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
