Bugfix: Private notes in emails & broken Signup (#1068)

* Bugfix: Private notes in emails

Private notes were sent in the emails as part of
conversation continuity. Fixed this issue.

Also made the changes to not even queue the mails
if message is a private note.

* Bugfix: Change issue with featurable in signup - passing array
* Bugfix: Added specs for checking  private notes being sent in email

app/models/concerns/featurable.rb

@@ -55,6 +55,6 @@ module Featurable
     return true if config.blank?
 
     features_to_enabled = config.value.select { |f| f[:enabled] }.map { |f| f[:name] }
-    enable_features(features_to_enabled)
+    enable_features(*features_to_enabled)
   end
 end