Unify socket closers. Don't put them all in one try-catch or some might remain.

lib/units/notify/hipchat.js

@@ -72,6 +72,11 @@ module.exports = function(options) {
     logger.LevelLabel[options.priority])
 
   lifecycle.observe(function() {
-    sub.close()
+    try {
+      sub.close()
+    }
+    catch (err) {
+      // No-op
+    }
   })
 }