Updates copyright to 2018

Gruntfile.js

@@ -15,7 +15,7 @@ module.exports = function(grunt) {
 				' * http://revealjs.com\n' +
 				' * MIT licensed\n' +
 				' *\n' +
-				' * Copyright (C) 2017 Hakim El Hattab, http://hakim.se\n' +
+				' * Copyright (C) 2018 Hakim El Hattab, http://hakim.se\n' +
 				' */'
 		},
 
@@ -164,7 +164,7 @@ module.exports = function(grunt) {
 	grunt.loadNpmTasks( 'grunt-retire' );
 	grunt.loadNpmTasks( 'grunt-sass' );
 	grunt.loadNpmTasks( 'grunt-zip' );
-	
+
 	// Default task
 	grunt.registerTask( 'default', [ 'css', 'js' ] );