Fix broken test and don't pass time units as strings but as ints.

cms/djangoapps/models/settings/course_grading.py

@@ -235,10 +235,10 @@ class CourseGradingModel(object):
 
     @staticmethod
     def convert_set_grace_period(descriptor):
-        # 5 hours 59 minutes 59 seconds => converted to iso format
+        # 5 hours 59 minutes 59 seconds => { hours: 5, minutes : 59, seconds : 59}
         rawgrace = descriptor.metadata.get('graceperiod', None)
         if rawgrace:
-            parsedgrace = {str(key): val for (val, key) in re.findall('\s*(\d+)\s*(\w+)', rawgrace)}
+            parsedgrace = {str(key): int(val) for (val, key) in re.findall('\s*(\d+)\s*(\w+)', rawgrace)}
             return parsedgrace
         else: return None