Added listen functionality so that Notifications can alert users about
filesystem changes. There is now a concept of Notification type, which
allows you to define groups for filesystem notifications.
Moved the file system changes to update_checker module.
Adding documentation.
Adding more comments.
Added more documentation.
Finished documentation.
Added more documentation and changed tests.
Fixed bugs and edited the tests.
Refactored into its own module.
Merge branch 'master' of github.com:rails/rails into notification_modifications
Overwrote the file update checker file with my file change listener
class.
Merge branch 'notification_modifications'