created choice creation route, controller action
succesful user creation now creates a session and redirects to user show page, failure redirects to root path
created a voting action for listings, matched a route to it so we can vote on choices, created a partial to render a voting form for each choice on a listing
fixed the choices voting form (and render call) so it isn't full of syntax errors
edited choice voting form so params returns {choice => choice.id}