Update npm dependencies

gulpfile.js

@@ -126,7 +126,7 @@ helpers.buildJS = function(site, minify) {
 	// Minify JS if required
 	if(minify) {
 		stream = stream.pipe(rename('index.min.js'))
-		               .pipe(uglify({preserveComments: 'license'}))
+		               .pipe(uglify({output: {comments: 'some'}}))
 		               .pipe(gulp.dest('assets/js'));
 	}
 	

package.json

@@ -6,23 +6,23 @@
 	"private": true,
 	
 	"dependencies": {
-		"element-closest": "2.0.1",
+		"element-closest": "2.0.2",
 		"flexismooth": "1.0.0",
-		"prismjs": "1.5.1",
+		"prismjs": "1.6.0",
-		"whatwg-fetch": "1.0.0"
+		"whatwg-fetch": "2.0.3"
 	},
 	"devDependencies": {
 		"del": "^2.2.1",
 		"gulp": "gulpjs/gulp.git#4.0",
-		"gulp-autoprefixer": "^3.1.0",
+		"gulp-autoprefixer": "^4.0.0",
-		"gulp-clean-css": "^2.0.12",
+		"gulp-clean-css": "^3.4.1",
 		"gulp-concat": "^2.6.0",
 		"gulp-header": "^1.8.7",
 		"gulp-include": "^2.3.1",
 		"gulp-preservetime": "^1.0.0",
 		"gulp-refresh": "^1.1.0",
 		"gulp-rename": "^1.2.2",
-		"gulp-sass": "^2.3.2",
+		"gulp-sass": "^3.1.0",
-		"gulp-uglify": "^1.5.3"
+		"gulp-uglify": "^3.0.0"
 	}
 }