todayBtn needs to be added to boolean list

[getup8]

todayBtn should be added to the list here:
https://github.com/asaglimbeni/django-datetime-widget/blob/master/datetimewidget/widgets.py#L146

Workaround is just to assign 'todayBtn': 'true' instead of 'todayBtn': True in the options dict.

[getup8]

Although I'm now reading the readme again:

If true , displays a "Today" button at the bottom of the datetimepicker to select the current date. If true, the "Today" button will only move the current date into view.

Is there a typo there and this field can take multiple values besides true and false?