Remove unneeded url and querystring modules

AFAICT these are just the exact same things that are in code Node so I
don't really see the point in keeping them, especially since both seem
unmaintained, i.e. out of sync.

All the functions used were added in the Node 0.1 days so this isn't
even semver-major.

Author: strugee

package.json

@@ -26,9 +26,7 @@
     "url": "https://github.com/patcon/hubot-github-repo-event-notifier/issues"
   },
   "dependencies": {
-    "coffee-script": "1.12.7",
-    "querystring": "^0.2.0",
-    "url": "^0.7.9"
+    "coffee-script": "1.12.7"
   },
   "devDependencies": {
     "chai": "^4.1.2",