readTime and timeParser are too greedy

[tel]

When parsing a non-delimited time expression like YYYYMMDD formatTime properly emits it by readTime fails to parse it.

>>> formatTime defaultTimeLocale "%Y%m%d" <$> getCurrentTime
"20130919"
>>> readTime defaultTimeLocale "%Y%m%d" "20130919"
*** Exception: not enough bytes

I believe this is because the underlying attoparsec parser is consuming the entire string while reading a number instead of limiting itself to just the first 4 digits.

[liyang]

Duplicate of #5.