I just tracked down an issue with datepicker-plus not working that turned out to be caused by this line in widgets.py:
'https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js',
This was importing a second (older) copy of jquery, which was conflicting with an earlier import. I've worked around it for now by making a copy of GoogleMapsAddressWidget with that line removed.