fix(package): update stripe to version 5.7.0

Closes #38

Author: greenkeeper[bot]

package.json

@@ -51,7 +51,7 @@
     "passport-twitter": "^1.0.3",
     "pug": "^2.0.0-beta6",
     "request": "^2.61.0",
-    "stripe": "^4.0.0",
+    "stripe": "^5.7.0",
     "tumblr.js": "^1.1.0",
     "twilio": "^3.3.0-edge",
     "twit": "^2.1.0",