- Tests

TLDR: Updates artist and adds maze builder.

- Add maze level builder (artist already exists.)
- Add toolbox, start blocks, and required blocks editor.
- Add maze builder.
- Name cancan fix before_filter so we can skip it where needed.
- Improve level editor form.
- Abstract some setup code so both script_level controller and levels controller can present levels in a similar way.
- Fix passing blocks to blockly if when there aren't any
- Use create action as entry point instead of custom actions.
- Fix start blocks to be able to see more of them.
- Only show blocks which for with the app being edited.
- Do a redirect upon custom turtle level (maze is already this way).