Some test failure modes can break *all* tests

[esiegerman]

Modify one of the testN.html files so that its JSON can't be parsed. Attempt to run the tests. They'll all fail. (One would, of course, expect that only the broken test would fail.)

The problem is that the JSON is parsed in beforeEach(), and errors there aren't handled the same way as errors in it().

This is only one example; basically, any error (I assume this means, any uncaught exception, but I haven't tested that) in beforeEach() will blow up all of the test cases.

See #25 for a fix.