Use mocha hooks to create server just before perform the test

test/acceptance/cache/cache_headers.js

@@ -9,8 +9,13 @@ var serverOptions = require('../../../lib/cartodb/server_options');
 var LayergroupToken = require('../../../lib/cartodb/models/layergroup-token');
 
 describe('get requests with cache headers', function() {
-    var server = new CartodbWindshaft(serverOptions);
-    server.setMaxListeners(0);
+    var server;
+
+    before(function () {
+        server = new CartodbWindshaft(serverOptions);
+        server.setMaxListeners(0);
+    });
+
 
     var keysToDelete;
     beforeEach(function() {

test/acceptance/cache/surrogate_keys_invalidation.js

@@ -30,7 +30,12 @@ describe('templates surrogate keys', function() {
         serviceId: FAKE_FASTLY_SERVICE_ID
     };
 
-    var server = new CartodbWindshaft(serverOptions);
+    var server;
+
+    before(function () {
+        server = new CartodbWindshaft(serverOptions);
+    });
+
 
     var templateOwner = 'localhost';
     var templateName = 'acceptance';