AbstractDateField.setDateFormat to correctly handle timezone name

Hi all,

Vaadin 8:
        DateTimeField df = new DateTimeField();
        df.setDateFormat("dd MMM yyyy - hh:mm:ss a z");

Vaadin 7:
        PopupDateField df = new PopupDateField();
        df.setDateFormat("dd MMM yyyy - hh:mm:ss a z");

Then select any date and time.

Expected output:
      The value shown to the user ends with 'CET' (in my case)

Actual output:
      The value shown to the user ends with 'UTC+1' (in my case)

Explanation:

The javadoc says: See SimpleDateFormat, and the below Java code prints something which ends with "CET" (in my case).
        SimpleDateFormat format = new SimpleDateFormat("dd MMM yyyy - hh:mm:ss a z");
        System.out.println(format.format(new Date()));

Appreciate your feedback.