Add unit test for JsonDataConverter class.
Adding of DataConverterAbstract class therefore AdmCrudFactory and JsonConverterModel is no more used.
Modification done because using of DataConverterAbstract class.
new helper class added : a simple factory for instantiate AdminModel
class use for automating the creation of relationship between two tables.
adding of parameter study_id when creating a new form so the system will able to create the relationship.