Description:
    Stubs out a new mailer and its views. Pass the mailer name, either
    CamelCased or under_scored, and an optional list of emails as arguments.

    This generates a mailer class in app/models, view templates in
    app/views/mailer_name, a unit test in test/unit, and fixtures in
    test/fixtures.

Example:
    `./script/generate mailer Notifications signup forgot_password invoice`

    creates a Notifications mailer class, views, test, and fixtures:
        Mailer:     app/models/notifications.rb
        Views:      app/views/notifications/signup.erb [...]
        Test:       test/unit/test/unit/notifications_test.rb
        Fixtures:   test/fixtures/notifications/signup [...]
