datepicker: better handling of prev and next buttons
datepicker: better handling of prev and next buttons

This renames the class settings more appropriately.  It also handles
the case where no default was given by putting ascii into the buttons.
This allows allows for setting the class at the component level.

All this is to allow more flexibility when specifying the prev/next
button content.

redding/romo,redding/romo,redding/romo