fix(package): update express-session to version 1.17.1

Closes #66

Author: greenkeeper[bot]

package.json

@@ -51,7 +51,7 @@
     "dataloader": "1.2.0",
     "dotenv": "2.0.0",
     "express": "4.14.1",
-    "express-session": "1.14.1",
+    "express-session": "1.17.1",
     "graphql": "0.9.0",
     "graphql-server-express": "^0.5.2",
     "graphql-subscriptions": "0.2.3",