Allow users to create Tools

:construction: :rotating_light: :construction_worker: :rotating_light: :construction:

This is current in progress, and it is kind of a beefy PR.

This introduces the `Tool`, a way for folks to share their various tools and plugins on Supermarket.

Trello card: https://trello.com/c/oV2dAj7h

The todos lives in the Trello card. :smile_cat: 
Gotcha then this makes sense. Am wondering if we should just make this spec pending and say `it 'should redirect to the tool'` or something so we remember to change it, not the end of the world if we don't, I just have a feeling it will get lost in the hustle.