Add a test to demonstrate the invalidity of a naive infinite loop detection algorithm

[karenetheridge]

It seems silly, but this was an error I had in my own implementation until
last week! :o

[Julian]

Seems reasonable, thanks! Why'd you put it in optional though? This looks required (though if we added more tests for infinite loop detection, those'd be optional)

[karenetheridge]

You're right - the spec says "Validators MUST NOT fall into an infinite loop.". This isn't a test of an actual infinite loop though, as we're unable to test that with the way the tests are set up today -- we'd need some way of saying "evaluating this schema should result in an error". Since this is only a test of a (possible) false positive, we should be able to assert that no evaluator detects this as an infinite loop.. so I guess this can be a mandatory test. I'll move it.

[Julian]

Someone may get confused at seeing a file called infinite-loop-detection.json which contains as you say a non-infinite loop, but I suppose it's fine for now. LGTM.

[karenetheridge]

I'm open to suggestions for a better filename.

[karenetheridge]

oops, I botched my force-push.. whoops.

[ssilverman]

Fixed some misspelled references in: #447