define name of value column

The name of the column containing the value is now part of the
csv settings. This allows us to use different names than "duration".

pdb-ui/src/main/java/org/lucares/pdbui/IngestionHandler.java

@@ -67,7 +67,7 @@ public final class IngestionHandler implements Callable<Void> {
         } else {
             in.reset();
             final CsvToEntryTransformer csvTransformer = new CsvToEntryTransformer(queue,
-                    CsvReaderSettings.create("@timestamp", ','));
+                    CsvReaderSettings.create("@timestamp", "duration", ','));
             csvTransformer.readCSV(in);
         }
     }