add EE audit changes class

lib/ee/audit/changes.rb

+module EE
+  module Audit
+    module Changes
+      def audit_changes(column, options = {})
+        return unless model.send("#{column}_changed?")
+
+        @column = column
+        @options = generate_options(options)
+
+        audit_event
+      end
+
+      protected
+
+      def model
+        raise NotImplementedError, "#{self} does not implement #{__method__}"
+      end
+
+      private
+
+      def generate_options(options)
+        options.tap do |options_hash|
+          options_hash[:column] = @column
+          options_hash[:action] = :update
+
+          unless options[:skip_changes]
+            options_hash[:from] = model.public_send("#{@column}_was")
+            options_hash[:to] = model.public_send("#{@column}")
+          end
+        end
+      end
+
+      def audit_event
+        AuditEventService.new(@current_user, model, @options).
+          for_changes.security_event
+      end
+    end
+  end
+end