convert timesheets to UTC with support for user timezone (#372)

config/packages/doctrine.yaml

@@ -17,6 +17,9 @@ doctrine:
 
         # With Symfony 3.3, remove the `resolve:` prefix
         url: '%env(resolve:DATABASE_URL)%'
+
+        types:
+            datetime: App\Doctrine\UTCDateTimeType
     orm:
         auto_generate_proxy_classes: '%kernel.debug%'
         naming_strategy: doctrine.orm.naming_strategy.underscore