add a datetime picker

Unfortunately the datetime picker does not support seconds. But it is
one of the few that support date and time and are flexible enough to
be used with VueJS.

data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java

@@ -59,7 +59,7 @@ public class DataStore implements AutoCloseable {
 
 		final long start = System.nanoTime();
 		final Stream<ListingFileEntry> files = folderStorage.list();
-		files// .parallel()
+		files.parallel()
 				.forEach(listingFileEntry -> {
 
 					listingFileEntry.unsetRelativePath(); // unset the path, so that we don't store it for every document (will