#118: Additional fixes to filter the row data.
Added _filterRowData to validateRow, else it will give a validation error.
Added _filterRowData _createDropdownAttributeOptions and _createMultiselectAttributeOptions, else it will add the symbol_for_clear_field to the options.
Implemented _filterRowData in Customers and Categories (Category Products and all product types not yet implemented).
Moved the config to general, since it also applies to Categories, Customers and Products.