Refactor contact mailer

- Send single email with new email in `to` and old email in `bcc` fields
- Remove `Que::Mailer` (#895)
- Add preview
- DRY templates
- Add tests
- Extract translations
- Remove useless specs

app/models/contact.rb

@@ -45,7 +45,6 @@ class Contact < ActiveRecord::Base
 
   before_validation :to_upcase_country_code
   before_validation :strip_email
-  before_update :manage_emails
 
   composed_of :identifier,
               class_name: 'Contact::Ident',
@@ -54,18 +53,6 @@ class Contact < ActiveRecord::Base
                                                                                 country_code: country_code) },
               mapping: [%w[ident code], %w[ident_type type], %w[ident_country_code country_code]]
 
-  def manage_emails
-    return nil unless email_changed?
-    return nil unless deliver_emails == true
-    emails = []
-    emails << [email, email_was]
-    emails = emails.flatten.uniq
-    emails.each do |e|
-      ContactMailer.email_updated(email_was, e, id, deliver_emails).deliver
-    end
-  end
-
-
   after_save :update_related_whois_records
 
   ORG = 'org'
@@ -77,8 +64,6 @@ class Contact < ActiveRecord::Base
   # From old registry software ("Fred"). No new contact can be created with this status
   PASSPORT = 'passport'
 
-  attr_accessor :deliver_emails
-
   #
   # STATUSES
   #

app/models/epp/contact.rb

@@ -145,8 +145,6 @@ class Epp::Contact < Contact
       self.legal_document_id = doc.id
     end
 
-    self.deliver_emails = true # turn on email delivery for epp
-
     ident_frame = frame.css('ident').first
 
     # https://github.com/internetee/registry/issues/576
@@ -175,7 +173,17 @@ class Epp::Contact < Contact
     self.upid = current_user.registrar.id if current_user.registrar
     self.up_date = Time.zone.now
 
-    super(at)
+    self.attributes = at
+
+    email_changed = email_changed?
+    old_email = email_was
+    updated = save
+
+    if updated && email_changed
+      ContactMailer.email_changed(contact: self, old_email: old_email).deliver_now
+    end
+
+    updated
   end
 
   def statuses_attrs(frame, action)