fix formation databag after app destroy, with test

Author: Gabriel Monroy

api/tasks.py

@@ -91,6 +91,7 @@ def build_app(app):
 def destroy_app(app):
     CM.purge_app(app.flat())
     app.delete()
+    app.formation.publish()
 
 
 @task

api/tests/app.py

@@ -95,6 +95,11 @@ def test_app_cm(self):
         response = self.client.delete(url)
         self.assertEqual(response.status_code, 204)
         self.assertFalse(os.path.exists(path))
+        formation_id = 'autotest'
+        path = os.path.join(settings.TEMPDIR, 'formation-{}'.format(formation_id))
+        with open(path) as f:
+            data = json.loads(f.read())
+        self.assertNotIn(app_id, data['apps'])
 
     def test_app_override_id(self):
         body = {'formation': 'autotest', 'id': 'myid'}