fix deprecations: add choices_as_values=true + flip contents of choice in ChoiceType

Export/Formatter/CSVFormatter.php

@@ -122,6 +122,7 @@ class CSVFormatter implements FormatterInterface
                  range(1, $nbAggregators),
                  range(1, $nbAggregators)
                  ),
+           'choices_as_values' => true,
            'multiple' => false,
            'expanded' => false
         ));