Clear attempts when clearing failures

Fixes #57. 

This actual fix is in 6464be206391eb6c6d1a327ea4bd1099f3a467de. I did a4c604a811af551521095df67cc4ab45fcfb65e2 and 5709dd12b710734900e3b9cdfe0d53152de5c97c to make RuboCop happy. I went with `greenify` since that's what it's called [in Stoplight Admin](https://github.com/orgsync/stoplight-admin/blob/9fab53244a1e03accf1e2daf21c9d5a583445df6/lib/sinatra/views/index.haml#L9).

@camdez, can you review this?