New layout of the calendar for the time fields #45

@gregrickaby please check if it is nice, I applied to all wordpress admin themes
I updated it to be date_picker to match what's in wp_locaize_script: https://github.com/WebDevStudios/CMB2/commit/0572902c90cc2a9da6f96ee7fda1fd70e806e0c2

But yes, please modify your PR to put those defaults back. If you want them removed, it needs to happen here: https://github.com/WebDevStudios/CMB2/blob/master/includes/CMB2_hookup.php#L152 and you'll need to provide a good explanation of why you think they should be removed.