The 'Customising generated forms' example contains a few issues that might confuse those who are copy/pasting the code.
1. No reference to the `geocode` library and where it comes from, added imports and revised API usage
2. `location = models.CharField()` requires the `max_length` attribute set
3. `FieldPanel('title')` added to content panels, otherwise testing this out causes error because no title or slug exists
These issues were flagged in #3737
This isn't necessary, since Django form media fills in static paths itself - and doing it at module level will break on startup with certain staticfiles configurations if collectstatic hasn't run yet. Fixes#3829
