Fix truncated parser testing

This change addresses #4.

The example ambiguity mentioned in the issue is the only one found so far - we'll skip that particular test. The others seem to work fine.

`python -c "import isodatetime; isodatetime.TimePointParser(allow_truncated=True).test()"` now passes (`allow_truncated=False` already passes).

@matthewrmshin, please review.