renamed res.respondTo() to res.format()

since you are not really responding with it,
its basically as switch

lib/response.js

@@ -300,7 +300,7 @@ res.type = function(type){
  *
  * Examples:
  *
- *    res.respondTo({
+ *    res.format({
  *      'text/plain': function(){
  *        res.type('text').send('hey');
  *      },
@@ -319,7 +319,7 @@ res.type = function(type){
  * @api public
  */
 
-res.respondTo = function(obj){
+res.format = function(obj){
   var keys = Object.keys(obj)
     , req = this.req
     , next = req.next
@@ -541,7 +541,7 @@ res.redirect = function(url){
   }
 
   // Support text/{plain,html} by default
-  this.respondTo({
+  this.format({
     'text/plain': function(){
       body = statusCodes[status] + '. Redirecting to ' + url;
     },

test/res.format.js

@@ -7,7 +7,7 @@ var express = require('../')
 var app = express();
 
 app.use(function(req, res, next){
-  res.respondTo({
+  res.format({
     'text/plain': function(){
       res.send('hey');
     },
@@ -30,7 +30,7 @@ app.use(function(err, req, res, next){
 })
 
 describe('req', function(){
-  describe('.respondTo(obj)', function(){
+  describe('.format(obj)', function(){
     it('should utilize qvalues in negotiation', function(done){
       request(app)
       .get('/')