When converting a scenario to JSON don't create a period for a variable, when the values for this period are always None in scenario.
When converting a scenario to JSON don't create a period for a variable, when the values for this period are always None in scenario.

adrienpacifico/openfisca-core,sgmap/openfisca-core,openfisca/openfisca-core,benjello/openfisca-core,benjello/openfisca-core,openfisca/openfisca-core