[WIP] Fixed #98, add Coveralls integration

[adinapoli]

I copied verbatim the options from my other repo, so that should do the trick, but I think we
will need to explicitly enable Foundation in Coveralls.

I think this requires one of the owner of the foundation repo (probably Vincent) to sign up and add the project, as I (as a member) can only enable my own fork, not the real deal:

[NicolasDP]

I have added it to coverall, is it still WIP ? https://coveralls.io/github/haskell-foundation/foundation

[adinapoli]

@NicolasDP Usually once Coveralls is fully set we should get it to post on each new open PR and get a new check, as below:

I suspect though, that since we added the permissions at a later stage we won't see those things now. Probably it's just easier to merge this and add small incremental tweaks until we get it to work 😉