Intervention Detail View

* adds related object overview in detail view
* adds comment field to payment model for 'Verwendungszweck'
* simplifies intervention urls
* adds translations

compensation/models.py

@@ -23,6 +23,12 @@ class Payment(BaseResource):
     """
     amount = models.FloatField(validators=[MinValueValidator(limit_value=0.00)])
     due_on = models.DateField(null=True)
+    comment = models.CharField(
+        max_length=1000,
+        null=True,
+        blank=True,
+        help_text="Refers to german money transfer 'Verwendungszweck'",
+    )
 
 
 class CompensationControl(BaseResource):