Add text version of unapproval email

app/mailers/emails/merge_requests.rb

@@ -65,7 +65,7 @@ module Emails
     def unapproved_merge_request_email(recipient_id, merge_request_id, unapproved_by_user_id)
       setup_merge_request_mail(merge_request_id, recipient_id)
 
-      @unapproved_by = User.find(approved_by_user_id)
+      @unapproved_by = User.find(unapproved_by_user_id)
       @unapproved_by_users = @merge_request.approved_by_users.map(&:name)
       mail_answer_thread(@merge_request, merge_request_thread_options(approved_by_user_id, recipient_id))
     end