Add csurf

package.json

@@ -48,6 +48,7 @@
     "connect-redis": "~2.1.0",
     "consolidate": "~0.11.0",
     "cookie-parser": "~1.3.4",
+    "csurf": "^1.9.0",
     "debug": "~2.2.0",
     "del": "~2.2.0",
     "diff": "~2.2.2",