OBGM-397 error message when opening add items to po sm dialog (#3862)
* OBGM-397 Fix findOrderItems receiving empty params
extract payload data from request.JSON instead of params
* OBGM-397 Change date_ordered table column datatype from varchar(255) to datetime
* OBGM-397 Check for orders before executing findAll query on OrderItems to prevent GORM from throwing an exception
