Fixing Plugin and Mailer default_url_options. Both the plugin hooks and Mailer were setting default_url_options incorrectly and causing ActionContoller::UrlWritter to cache the settings on the module (mattr_accessor) causing several url generators to fail in either the plugin hooks or the Mailer. * Replaced Mailer's use of the default_url_options accessor with the proper class method * Replaced Hook's use of the default_url_options accessor with the proper class method on the ViewListener class * Added a test to reproduce the bugs in the Mailer when a hook is registered (thanks Chaoqun Zou) #2542 git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@2522 e93f8b46-1217-0410-a6f0-8f06a7374b81