added impairment scaffold to facilitate the association of disabilities with a particular user.
recreated impairment scaffold because disability_id and user_id did not need _ID at the end, since they are input by default. so previous version had user_id_id.
added radio buttons for severity when creating new impairment, add select drop displaying collection of disablities. added code in users controller to get all impairments associated with a user.
added associations.
listed impairment records on the user profile page with an option to add new impairment.