Feature Request: Add 'capabilities' condition

I'm very familiar with roles and capabilities. I use custom roles and caps on most sites as I build large ones with many editing users. Because I have many roles, it's easier to do a capability check than a role check. For example, I have a settings page which only certain roles can edit: administrator, webmaster, seo admin, analytics admin. Instead of adding all those roles, just doing a manage_options cap check works better.

I looked at the source for this extension and was easily able to add support for this:

In file class-mb-include-exclude.php
Line 75, add , 'capability' to the array.
Line 253, insert

  /**
   * Check by current user capability.
   *
   * @param array|string $capabilities List of user capabilities. Array or CSV.
   *
   * @return bool
   */
  protected static function check_capability( $capabilities ) {
    $user = wp_get_current_user();
    $capabilities = array_map( 'strtolower', self::csv_to_array( $capabilities ) );

    foreach ( $capabilities as $capability ) {
      if ( $user->has_cap( $capability ) ) {
        return true;
      }
    }

    return false;
  }

Then in your meta box config, add:

      'include' => array(
        'capability' => 'manage_options',
      ),