added notify class and mail action for inform

app/services/contact_notification.rb

@@ -0,0 +1,17 @@
+module ContactNotification
+  extend self
+
+  def notify_registrar(domain:, text:)
+    domain.registrar.notifications.create(text: text)
+  end
+
+  def notify_tech_contact(domain:)
+    text = "DNSKEYS for #{domain.name} are invalid!"
+    domain.tech_domain_contacts.each do |tech|
+      contact = Contact.find(tech.id)
+
+      ContactInformMailer.notify(contact: contact, subject: text)
+    end
+  end
+
+end