date_format doesn't support time formatting

[lorin]

date_format returns zeros for %H, %M and %S

>>> from datetime import datetime
>>> import time
>>> from mizani import date_format

>>> fmt = "%Y-%m-%d %H:%M:%S"
>>> ts = datetime(2017,12,1,16,5,7)

>>> ts.strftime(fmt)
'2017-12-01 16:05:07'
>>> date_format(fmt)([ts])
['2017-12-01 00:00:00']

I looked to see if there was a different formatter for datetimes instead of just dates, but I couldn't find one.

[has2k1]

Fix released in v0.4.3.

[lorin]

Wow, that was fast!