Changed the config parameter.  The session's _get_time() function has also changed.
diff --git a/application/config/config.php b/application/config/config.php
index 12ef77c..fd6a1ae 100644
--- a/application/config/config.php
+++ b/application/config/config.php
@@ -359,7 +359,7 @@
 
 /*
 |--------------------------------------------------------------------------
-| Master Timezone
+| Master Time Reference
 |--------------------------------------------------------------------------
 |
 | You can set any PHP supported timezones to be the master timezone when
@@ -367,7 +367,7 @@
 | time.
 |
 */
-$config['timezone'] = 'local';
+$config['time_reference'] = 'local';
 
 
 /*