Improve js and add native language support for datepicker and calendar

app/Locale/de_DE/translations.php

@@ -650,44 +650,6 @@ return array(
     'Filter by column' => 'Spalte filtern',
     'Filter by status' => 'Status filtern',
     'Calendar' => 'Kalender',
-    'Today' => 'Heute',
-    'Jan ' => 'Jan',
-    'Feb' => 'Feb',
-    'Mar' => 'Mar',
-    'Apr' => 'Apr',
-    'May' => 'Mai',
-    'Jun' => 'Jun',
-    'Jul' => 'Jul',
-    'Aug' => 'Aug',
-    'Sep' => 'Sep',
-    'Oct' => 'Okt',
-    'Nov' => 'Nov',
-    'Dec' => 'Dez',
-    'January' => 'Januar',
-    'February' => 'Februar',
-    'March' => 'März',
-    'April' => 'April',
-    'June' => 'Juni',
-    'July' => 'Juli',
-    'August' => 'August',
-    'September' => 'September',
-    'October' => 'Oktober',
-    'November' => 'November',
-    'December' => 'Dezember',
-    'Sunday' => 'Sonntag',
-    'Monday' => 'Montag',
-    'Tuesday' => 'Dienstag',
-    'Wednesday' => 'Mittwoch',
-    'Thursday' => 'Donnerstag',
-    'Friday' => 'Freitag',
-    'Saturday' => 'Samstag',
-    'Sun' => 'So',
-    'Mon' => 'Mo',
-    'Tue' => 'Di',
-    'Wed' => 'Mi',
-    'Thu' => 'Do',
-    'Fri' => 'Fr',
-    'Sat' => 'Sa',
     'Next' => 'Nächste',
     // '#%d' => '',
     'Filter by color' => 'Farbe filtern',