Fix for authHeader not including extra params

Ref: ciaranj#366

Author: codersmith

lib/oauth.js

@@ -571,11 +571,15 @@ exports.OAuth.prototype.signUrl= function(url, oauth_token, oauth_token_secret,
   return parsedUrl.protocol + "//"+ parsedUrl.host + parsedUrl.pathname + "?" + query;
 };
 
-exports.OAuth.prototype.authHeader= function(url, oauth_token, oauth_token_secret, method) {
+exports.OAuth.prototype.authHeader= function(url, oauth_token, oauth_token_secret, method, extra_params) {
   if( method === undefined ) {
     var method= "GET";
   }
 
-  var orderedParameters= this._prepareParameters(oauth_token, oauth_token_secret, method, url, {});
+  if( extra_params === undefined ) {
+    var extra_params= {};
+  }
+
+  var orderedParameters= this._prepareParameters(oauth_token, oauth_token_secret, method, url, extra_params);
   return this._buildAuthorizationHeaders(orderedParameters);
 };