Bug 14074: Format 'suggested on' date in suggestion list correctly

Bug 14074: Format 'suggested on' date in suggestion list correctly

One of the dates (suggested on) in the list of
suggestions in staff is not correctly formatted.

To test:
- Create one or many suggestions
- Check the list of suggestion, especially in the
  'Suggested by - on' column
- Verify the date is not displayed according to
  the dateformat preference
- Apply patch
- Verify the problem is fixed

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>