Add seed values support for Query Builder order_by

(feature request #1987)
diff --git a/system/database/drivers/sqlite/sqlite_driver.php b/system/database/drivers/sqlite/sqlite_driver.php
index 8541173..23f287b 100644
--- a/system/database/drivers/sqlite/sqlite_driver.php
+++ b/system/database/drivers/sqlite/sqlite_driver.php
@@ -53,9 +53,9 @@
 	/**
 	 * ORDER BY random keyword
 	 *
-	 * @var	string
+	 * @var	array
 	 */
-	protected $_random_keyword = ' Random()'; // database specific random keyword
+	protected $_random_keyword = array('RANDOM()', 'RANDOM()');
 
 	// --------------------------------------------------------------------