Show localized date over top of date input

Also move datepicker logic into edit_books.js and edit_books.js below the datepicker file declaration(s)

cps/static/js/edit_books.js

@@ -1,8 +1,23 @@
 /**
  * Created by SpeedProg on 05.04.2015.
  */
-/* global Bloodhound */
+/* global Bloodhound, language */
 
+if (!Modernizr.inputtypes.date) {
+    $('#pubdate').datepicker({
+        format: 'yyyy-mm-dd',
+        language: language
+    }).on('change', function () {
+        // Show localized date over top of the standard YYYY-MM-DD date
+        let pubDate, results;
+        if ((results = /(\d{4})[-\/\\](\d{1,2})[-\/\\](\d{1,2})/.exec(this.value))) { // YYYY-MM-DD
+            pubDate = new Date(results[1], parseInt(results[2], 10)-1, results[3]) || new Date(this.value);
+        }
+        $('#fake_pubdate')
+            .val(pubDate.toLocaleDateString(language))
+            .removeClass('hidden');
+    }).trigger('change');
+}
 
 /*
 Takes a prefix, query typeahead callback, Bloodhound typeahead adapter