get_ and set_value handle cmi.score.scaled (#58)

cmi.score.scaled in SCORM 2004 packages should be a
decimal between 0 and 1 reflecting a percentage score
(Actually cmi.score.scaled can have -1 to 1 but Open edX
shouldn't allow negative scores)

Fix Issue #55

openedxscorm/scormxblock.py

@@ -417,6 +417,8 @@ def scorm_get_value(self, data, _suffix):
             return {"value": self.success_status}
         if name in ["cmi.core.score.raw", "cmi.score.raw"]:
             return {"value": self.lesson_score * 100}
+        if name == "cmi.score.scaled":
+            return {"value": self.lesson_score}
         if name in ["cmi.core.student_id", "cmi.learner_id"]:
             return {"value": self.get_current_user_attr("edx-platform.user_id")}
         if name in ["cmi.core.student_name", "cmi.learner_name"]:
@@ -457,6 +459,8 @@ def set_value(self, data):
             completion_status = value
         elif name in ["cmi.core.score.raw", "cmi.score.raw"] and self.has_score:
             lesson_score = parse_validate_positive_float(value, name) / 100.0
+        elif name == "cmi.score.scaled" and self.has_score:
+            lesson_score = parse_validate_positive_float(value, name)
         elif name == "cmi.progress_measure":
             completion_percent = parse_validate_positive_float(value, name)