Introduced multilayer computation

Created by: stefanoborini

Introduces the possibility to perform more than one layer of DataSources

force_bdss/io/tests/test_workflow_writer.py

@@ -45,7 +45,7 @@ class TestWorkflowWriter(unittest.TestCase):
         self.assertIn("version", result)
         self.assertIn("workflow", result)
         self.assertIn("mco", result["workflow"])
-        self.assertIn("data_sources", result["workflow"])
+        self.assertIn("execution_layers", result["workflow"])
         self.assertIn("kpi_calculators", result["workflow"])
 
     def test_write_and_read(self):