Travis setup and minor cleanup
diff --git a/system/database/DB.php b/system/database/DB.php
index 96e4955..e943423 100755
--- a/system/database/DB.php
+++ b/system/database/DB.php
@@ -138,7 +138,12 @@
 		class CI_DB extends CI_DB_driver { }
 	}
 
-	require_once(BASEPATH.'database/drivers/'.$params['dbdriver'].'/'.$params['dbdriver'].'_driver.php');
+	// Load the DB driver
+	$driver_file = BASEPATH.'database/drivers/'.$params['dbdriver'].'/'.$params['dbdriver'].'_driver.php';
+
+	if ( ! file_exists($driver_file)) show_error('Invalid DB driver');
+
+	require_once($driver_file);
 
 	// Instantiate the DB adapter
 	$driver = 'CI_DB_'.$params['dbdriver'].'_driver';