Update formatters

lib/format/css.js

@@ -1,10 +1,7 @@
 'use strict';
 
 module.exports = function (codes) {
-	return function customizedFormatHTML(req, res, body) {
-		if (typeof (body) === 'string')
-			return body;
-
-		return '';
+	return function customizedFormatCSS(req, res, body) {
+        return res.formatters['text/html'](req, res, body);
 	};
 };

lib/format/html.js

@@ -5,6 +5,8 @@ module.exports = function (codes) {
 		if(typeof body === 'object') {
 			return res.formatters['application/json'](req, res, body);
 		} else {
+            body = body.toString();
+            res.setHeader('Content-Length', Buffer.byteLength(body));
 			return body;
 		}
 	};

lib/format/json.js

@@ -25,7 +25,6 @@ module.exports = function (codes) {
 
 		var data = JSON.stringify(body);
 		res.setHeader('Content-Length', Buffer.byteLength(data));
-		res.setHeader('Content-Type', 'application/json');
 
 		return data;
 	};

lib/format/png.js

@@ -2,6 +2,10 @@
 
 module.exports = function (codes) {
 	return function customizedFormatPNG(req, res, body) {
-		return body;
+        if(typeof body === 'object') {
+            return res.formatters['application/json'](req, res, body);
+        } else {
+            return body;
+        }
 	};
 };