chore(package): update express to version 4.17.1

Closes #35

Author: greenkeeper[bot]

package.json

@@ -42,7 +42,7 @@
     "eslint": "^3.19.0",
     "eslint-plugin-import": "^2.2.0",
     "eslint-watch": "^3.0.1",
-    "express": "4.15.2",
+    "express": "4.17.1",
     "extract-text-webpack-plugin": "^2.1.0",
     "html-webpack-plugin": "^2.28.0",
     "jsdom": "^10.0.0",