Remove bottle-formula validation test

This is not really necessary and only serves as validation that will need to updated if model choices ever change.

core/models.py

@@ -252,13 +252,6 @@ class Feeding(models.Model):
         validate_duration(self)
         validate_unique_period(Feeding.objects.filter(child=self.child), self)
 
-        # "Formula" Type may only be associated with "Bottle" Method.
-        if self.type == 'formula' and self.method != 'bottle':
-            raise ValidationError(
-                {'method':
-                 _('Only "Bottle" method is allowed with "Formula" type.')},
-                code='bottle_formula_mismatch')
-
 
 class Note(models.Model):
     model_name = 'note'

core/tests/tests_forms.py

@@ -263,16 +263,9 @@ class FeedingFormsTestCase(FormsTestCaseBase):
             'start': self.localtime_string(start),
             'end': self.localtime_string(end),
             'type': 'formula',
-            'method': 'left breast',
+            'method': 'bottle',
             'amount': 0
         }
-        page = self.c.post('/feedings/add/', params)
-        self.assertEqual(page.status_code, 200)
-        self.assertFormError(
-            page, 'form', 'method',
-            'Only "Bottle" method is allowed with "Formula" type.')
-
-        params.update({'method': 'bottle'})
         page = self.c.post('/feedings/add/', params, follow=True)
         self.assertEqual(page.status_code, 200)
         self.assertContains(