Specify KPIs at the MCO level

Created by: stefanoborini

Changes the model so that KPIs are now defined at the MCO level, instead of the data sources.

Fixes #145 (closed)

force_bdss/core/data_value.py

-from traits.api import HasStrictTraits, Any, String, Enum, Bool
+from traits.api import HasStrictTraits, Any, String, Enum
 
 
 class DataValue(HasStrictTraits):
@@ -22,9 +22,6 @@ class DataValue(HasStrictTraits):
     #: A flag for the quality of the data.
     quality = Enum("AVERAGE", "POOR", "GOOD")
 
-    # Set by the engine. True if the data value contains a KPI.
-    is_kpi = Bool(False)
-
     def __str__(self):
 
         s = "{} {} = {}".format(
@@ -35,7 +32,4 @@ class DataValue(HasStrictTraits):
 
         s += " ({})".format(str(self.quality))
 
-        if self.is_kpi:
-            s += " (KPI)"
-
         return s