Switch out the datepicker, now using react-dates for accessibility
reasons:

 1. It was easier to make react-dates work well with a
keyboard then datepicker
 2. It was easier to properly markup the react-dates datepicker with
the correct aria tags
 3. react-datepicker had some strange onBlur issues preventing the
calendar from properly closing that react-dates handles properly

Conflicts:
	frontend/yarn.lock