Removes model-schema.json which is now provided as part of hubTemplate
Adds file_format property to admin-schema.json as well as to round objects in tasks-schema.json to allow for round specific setting of accepted file formats overriding hub wide setting.
file_formatproperty toadmin-schema.jsonas well as to round objects intasks-schema.jsonto allow for round specific setting of accepted file formats overriding hub wide setting.