Add Quickcheck to spec to motivate dev dependency

[DrBoolean]

Over at #68 I had an issue with using Id to express a traversable law - i.e. using an implementation within the spec.

At #66 @phadej suggested we motivate some reason to depend on the spec so we can chart it's use and have a reason for versioning.

I'd like to see a law quickcheck test script included in the spec. Something like: https://github.com/folktale/laws

That would allow people to add fantasy-land as a dev dependency as well as give me a reason to include Id

My vision is something like:

var fl = require('fantasy-land')
fl.quickcheck(MyType, [fl.functor, fl.traversable, fl.foldable]);

I also believe it makes sense to do the derivations from fl, but that might be overboard.

[phadej]

There was a PR once: #61

[SimonRichardson]

I've moved the quick check lib to fantasy land. It's not as simple as what you've got in your example, but could easily be added via a wrapper!

https://github.com/fantasyland/fantasy-check

[SimonRichardson]

I'm going to close this, as we do have a checking library for it now. You can suggest helper methods (see @DrBoolean idea above) in that library now :)