close #114

introduced "Failed" status for instructor
polite wording for member

apiserver/apiserver/api/serializers.py

@@ -569,6 +569,7 @@ class TrainingSerializer(serializers.ModelSerializer):
         'Waiting for payment',
         'Withdrawn',
         'Rescheduled',
+        'Failed',
         'No-show',
         'Attended',
         'Confirmed'
@@ -1076,4 +1077,4 @@ class MyLoginSerializer(LoginSerializer):
         if not user:
             raise ValidationError(dict(password='Incorrect password. Check caps lock.'))
 
-        return user
+        return user