LICENSE: Update year to 2018

LICENSE

 The MIT License (MIT)
 
-Copyright (c) 2014-2017 syuilo
+Copyright (c) 2014-2018 syuilo
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

src/const.json

 {
-	"copyright": "Copyright (c) 2014-2017 syuilo",
+	"copyright": "Copyright (c) 2014-2018 syuilo",
 	"themeColor": "#ff4e45",
 	"themeColorForeground": "#fff"
 }

webpack/plugins/banner.ts

@@ -3,7 +3,7 @@ import * as webpack from 'webpack';
 
 export default version => new webpack.BannerPlugin({
 	banner:
-		`Misskey v${version} | MIT Licensed, (c) syuilo 2014-2017\n` +
+		`Misskey v${version} | MIT Licensed, (c) syuilo 2014-2018\n` +
 		'https://github.com/syuilo/misskey\n' +
 		`built by ${os.hostname()} at ${new Date()}\n` +
 		'hash:[hash], chunkhash:[chunkhash]'