puts all the :year, :month, and other columns into div.row.
also fixes the grid column styling - date input fragments should fill in
whole 12 grid units (see: Timeish::FRAGMENT_CLASSES,
DateSelectInput::FRAGMENT_CLASSES, TimeSelectInput::FRAGMENT_CLASSES
div.row
.Timeish::FRAGMENT_CLASSES
,DateSelectInput::FRAGMENT_CLASSES
,TimeSelectInput::FRAGMENT_CLASSES