Redmine 2.2.0

Hey Sébastien!

I have adjusted your plugin to work with Rails 2.2.0.

I am not sure of modification in
https://github.com/barda/redmine_email_notification_content_filter/blob/master/lib/mailer_patch.rb#L43
when I set TO recipients: that recipients are only the issue.recipients?

Regards and season's greetings,
Antonio