New ideas and changes

New ideas and changes:
- DatePicker of the WordPress library, removed the file;
- New path for backgroud-image in CSS/SASS;
- Support for translations;
- Added new field Hidden;
```
array(
     'id'   => $prefix . 'wordpress',
     'type' => 'hidden',
),
```
- Added new path of directory and URL, it can be set in the functions.php;
```
/**
 * Initialize the metabox class.
 */
function cmb_initialize_cmb_meta_boxes() {
    if (!class_exists( 'cmb_Meta_Box' )) {
        // Custom path URL
        define( 'CMB_META_BOX_URL', trailingslashit( get_stylesheet_directory_uri() . '/lib/Custom-Metaboxes-and-Fields-for-WordPress' ) );

        // Custom path DIR
        define( 'CMB_META_BOX_DIR', trailingslashit( TEMPLATEPATH . '/lib/Custom-Metaboxes-and-Fields-for-WordPress' ) );

        require_once 'lib/Custom-Metaboxes-and-Fields-for-WordPress/init.php';
    }
}
add_action( 'init', 'cmb_initialize_cmb_meta_boxes', 9999 );
```
- Responsive video;