Sort network names in the register new host form

The sorting of the models was done in the utils.get_model_choices
funtion but a specific query was passed to not display admin_only networks.

The sorting is now done even when passing a specific query to
get_model_choices.

JIRA INFRA-284

app/utils.py

@@ -140,7 +140,8 @@ def get_model_choices(model, allow_none=False, attr='name', query=None):
     if allow_none:
         choices = [(None, '')]
     if query is None:
-        query = model.query.order_by(getattr(model, attr))
+        query = model.query
+    query = query.order_by(getattr(model, attr))
     choices.extend([(str(instance.id), getattr(instance, attr)) for instance in query.all()])
     return choices