Allow only exactly irc version 0.5.0

Since the >0.5.0 versions produce the following error:
martynsmith/node-irc#495

Author: precla

package.json

@@ -37,7 +37,7 @@
     "countdown": "^2.6.0",
     "get-youtube-id": "^1.0.0",
     "google": "^2.1.0",
-    "irc": "^0.5.0",
+    "irc": "0.5.0",
     "irc-colors": "^1.2.0",
     "lodash": "^4.2.1",
     "moment": "^2.11.2",