Update license date (Cog-Creators#1240)

LICENSE

@@ -632,7 +632,7 @@ state the exclusion of warranty; and each file should have at least
 the "copyright" line and a pointer to where the full notice is found.
 
     Red - A fully customizable Discord bot
-    Copyright (C) 2015-2017  Twentysix
+    Copyright (C) 2015-2018 Twentysix
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -652,7 +652,7 @@ Also add information on how to contact you by electronic and paper mail.
   If the program does terminal interaction, make it output a short
 notice like this when it starts in an interactive mode:
 
-    Red-DiscordBot  Copyright (C) 2015-2017  Twentysix
+    Red-DiscordBot  Copyright (C) 2015-2018  Twentysix
     This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
     This is free software, and you are welcome to redistribute it
     under certain conditions; type `show c' for details.
@@ -671,4 +671,4 @@ into proprietary programs.  If your program is a subroutine library, you
 may consider it more useful to permit linking proprietary applications with
 the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.