Update dependencies, remove hubot-rss-reader

Updates hubot-kredits for the MediaWiki changes, among others.

Unfortunately, I wasn't able to get hubot-rss-reader to npm-install
anymore.

external-scripts.json

@@ -8,7 +8,6 @@
   "hubot-plusplus",
   "hubot-tell",
   "hubot-seen",
-  "hubot-rss-reader",
   "hubot-incoming-webhook",
   "hubot-yubikey-invalidation",
   "hubot-kredits",