function register_allergen( allergen_nid ) {
    var new_state, current_state;
    current_state = $('#allergen-'+allergen_nid+'-status').attr('class');

    if( current_state == 'safe' ) {
        new_state = 'allergic';
    } else {
        new_state = 'safe';
    }
    
    $.getJSON("http://demo.travelgoats.com/fallergy/ajax-allergen-hotbar-update",{allergen_nid: allergen_nid, new_state: new_state, ajax: 'true'}, function(j){
        $('#allergen-'+allergen_nid+'-status').removeClass('allergic');
        $('#allergen-'+allergen_nid+'-status').removeClass('safe');
        $('#allergen-'+allergen_nid+'-status').addClass(j);
    })
}