Improve error handling

lib/core/settle.js

@@ -1,5 +1,7 @@
 'use strict';
 
+var createError = require('./createError');
+
 /**
  * Resolve or reject a Promise based on response status.
  *
@@ -13,6 +15,8 @@ module.exports = function settle(resolve, reject, response) {
   if (!response.status || !validateStatus || validateStatus(response.status)) {
     resolve(response);
   } else {
-    reject(response);
+    var error = createError('Request failed with status code ' + response.status, response.config);
+    error.response = response;
+    reject(error);
   }
 };