set application timezone early in application constructor, set default of UTC if no timezone is configured at all (not in app config nor in php.ini)

yii/base/Application.php

@@ -85,6 +85,10 @@ class Application extends Module
 			throw new InvalidConfigException('The "basePath" configuration is required.');
 		}
 		
+		if (isset($config['timeZone']) || !ini_get('date.timezone')) {
+			$this->setTimeZone( \yii\helpers\ArrayHelper::remove($config,'timeZone','UTC') );
+		}
+
 		$this->registerErrorHandlers();
 		$this->registerCoreComponents();