Use legacy url from peliasConfig

routes/legacy.js

@@ -1,12 +1,12 @@
 var proxy = require('express-http-proxy');
 
-var sendToLegacy = proxy('pelias.mapzen.com', {
+function addRoutes(app, peliasConfig) {
+  var sendToLegacy = proxy(peliasConfig.legacyUrl, {
     forwardPath: function(req, res) {
       return require('url').parse(req.url).path;
     }
   });
 
-function addRoutes(app) {
   // api root
   app.get( '/', sendToLegacy );