Bug 9374: Only 0.00 prices must have class error in basket.tt

A regexp '^0' in basket.tt is used to give the class "error" to null prices.
It is wrong, because it matches prices like "0.15". It should only match "0.00".

To test :
- apply the patch
- display a basket with an order with a price between 0 and 1 (like "0.50") and an order with a price stricty null ("0.00")
- only the "0.00" price should be displayed in red

Signed-off-by: Cedric Vita <cedric.vita@dracenie.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>