Remove image alignment CSS from featured image

new_gist_file.php

// Remove Image Alignment from Featured Image
// @link http://www.billerickson.net/genesis-featured-image-alignment/
add_filter( 'genesis_attr_entry-image', 'be_remove_image_alignment' );
function be_remove_image_alignment( $attributes ) {
  $attributes['class'] = str_replace( 'alignleft', 'alignnone', $attributes['class'] );
	return $attributes;
}