Remove disconnect handlers property

Author: mbabker

src/DatabaseDriver.php

@@ -203,12 +203,6 @@ abstract class DatabaseDriver implements DatabaseInterface, Log\LoggerAwareInter
 	 */
 	private $logger;
 
-	/**
-	 * @var    callable[]  List of callables to call just before disconnecting database
-	 * @since  __DEPLOY_VERSION__
-	 */
-	protected $disconnectHandlers = array();
-
 	/**
 	 * Get a list of available database connectors.  The list will only be populated with connectors that both
 	 * the class exists and the static test method returns true.  This gives us the ability to have a multitude