Update to AppointmentMailer

The two appointment mailer class have been merged.  The subject has been changed to use config.stylist_name which should be added to config/environments/development.rb, along with config.from_email_address, for testing.  The templates by @veronicacannon have been renamed for the new method name and duplicated for the to_stylist mailer method.  If different templates are wanted for the stylist emails the templates will need to be updated.