unicode fix for getGuessStatuses + a few unit tests

[jleverenz]

Some unit tests around unicode handling. #250 should go in first.

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[jleverenz]

Rebased now that #250 is in. This PR also contains a bugfix for getGuessStatuses unicode support.

[gheja]

Oh, wow, thanks for creating these tests! I've been struggling to come up with a well maintanable way to test the cases (I have little experience with react so far), now I can build upon your code.