/**
  * See: http://plugin.michael-simpson.com/?page_id=101
  * Called by install() to create any database tables if needed.
  * Best Practice:
  * (1) Prefix all table names with $wpdb->prefix
  * (2) make table names lower case only
  * @return void
  */
 protected function installDatabaseTables()
 {
     Entry::install_table();
 }