Create the Tools show API endpoint

:fork_and_knife: :meat_on_bone: :curry:

This allows access to the information for a specific Tool via the API.

An example request:

     GET /api/v1/tools/berkshelf

This will return the information for the berkshelf tool on Supermarket.

Unlike the rest of the API, this commit commit does not add view level specs. I
feel that the API spec properly tests the signature of what is output via the
API, which, to me, feels like the same expectations as the view specs.
This feels super nit-picky so bear with me but I feel like there should be an extra return after this context block. Based on your other API specs I presume you also meant there to be one here so :smile: