Extract io layer to writer/reader class

Created by: stefanoborini

Extracted IO layer into writer and reader classes, and create model objects with support from the bundles.

force_bdss/core_plugins/csv_extractor/csv_extractor/csv_extractor_model.py

@@ -8,12 +8,3 @@ class CSVExtractorModel(BaseDataSourceModel):
     row = Int()
     column = Int()
     cuba_type = String()
-
-    @classmethod
-    def from_json(cls, json_data):
-        return cls(
-            filename=json_data["filename"],
-            row=json_data["row"],
-            column=json_data["column"],
-            cuba_type=json_data["cuba_type"]
-        )