Cms yml

More of a proof-of-concept than anything really usable right now, but you can make edits and see the footer text change!

How it works:
- ```en.yml``` holds the text
- Render the text in views by using the ```t``` helper (see ```_footer.html.slim``` and ```en.yml``` for examples)
- A form just reads/writes from ```en.yml``` to make edits to the app