Added string method to DataSourceResult and DataSourceParameters

Created by: stefanoborini

force_bdss/data_sources/data_source_parameters.py

@@ -4,3 +4,12 @@ from traits.api import HasStrictTraits, Array, List, String
 class DataSourceParameters(HasStrictTraits):
     value_types = List(String)
     values = Array(shape=(None,))
+
+    def __str__(self):
+        return """
+        DataSourceParameters
+        value_types:
+        {}
+        values:
+        {}
+        """.format(str(self.value_types), str(self.values))