Move branding info from model

This was an awkward property to have in a model class because
- it’s presentation not data about the object
- it munged together data from a different object, so it wasn’t well
  encapsulated

This commit moves the logic to the template, where it can reference the
`Organisation` and `User` models directly.

app/models/organisation.py

@@ -101,9 +101,6 @@ class Organisation(JSONModel):
             self.request_to_go_live_notes = None
             self.email_branding_id = None
 
-    def as_info_for_branding_request(self, fallback_domain):
-        return self.name or 'Can’t tell (domain is {})'.format(fallback_domain)
-
     @property
     def organisation_type_label(self):
         return dict(self.TYPES).get(self.organisation_type)

app/templates/support-tickets/branding-request.txt

@@ -1,4 +1,8 @@
-Organisation: {{ current_service.organisation.as_info_for_branding_request(current_user.email_domain) }}
+Organisation: {% if current_service.organisation -%}
+  {{ current_service.organisation.name }}
+{%- else -%}
+  Can’t tell (domain is {{ current_user.email_domain }})
+{%- endif %}
 Service: {{ current_service.name }}
 {{ url_for('main.service_dashboard', service_id=current_service.id, _external=True) }}