Removed on blur/change JS

the blur/change function was closing the date picker.  The result of this is that the user cannot paginate between months.
Updated fitelds.html.twig 1) widget_addon was updated to use widget_addon_append/prepend 2) Fixed an html validation issue in file_widget
Merge pull request #601 from chrisjohnson00/patch-1

datepicker js updates & widget_addon_prepend/append fix for datepicker and file_widget