Added default option for objective setting

force_bdss/core/kpi_specification.py

@@ -8,4 +8,4 @@ class KPISpecification(HasStrictTraits):
     name = Identifier()
 
     #: The expected outcome of the procedure relative to this KPI.
-    objective = Enum("", "MINIMISE")
+    objective = Enum("", "DEFAULT", "MINIMISE")