Refactor inactive contact archivation

Fixes #956

app/models/inactive_contacts.rb

@@ -0,0 +1,14 @@
+class InactiveContacts
+  attr_reader :contacts
+
+  def initialize(contacts = Contact.archivable)
+    @contacts = contacts
+  end
+
+  def archive
+    contacts.each do |contact|
+      contact.archive
+      yield contact if block_given?
+    end
+  end
+end