Removing pug plugin

- Due to this:
https://gitter.im/cake-build/cake?at=56410e2d8b872257348e17ef
- If/when this PR gets accepted:
hubot-archive/hubot-pugme#1
- We can think about adding this back in

external-scripts.json

@@ -6,7 +6,6 @@
   "hubot-google-translate",
   "hubot-group-alias",
   "hubot-karma-classic",
-  "hubot-pugme",
   "hubot-maps",
   "hubot-redis-brain",
   "hubot-rules",

package.json

@@ -16,7 +16,6 @@
     "hubot-heroku-keepalive": "^1.0.0",
     "hubot-karma-classic": "~1.0.1",
     "hubot-maps": "0.0.2",
-    "hubot-pugme": "^0.1.0",
     "hubot-redis-brain": "0.0.3",
     "hubot-rules": "^0.1.1",
     "hubot-scripts": "^2.16.2",