Hipay : Fix PNM-2505, PNM-2443, PNM-1909, PNM-1907 and PNM-735

Fix PNM-2505, PNM-2443, PNM-1909, PNM-1907 and PNM-735 on HiPay addon
http://forge.prestashop.com/browse/PNM-2505
http://forge.prestashop.com/browse/PNM-2443
http://forge.prestashop.com/browse/PNM-1909
http://forge.prestashop.com/browse/PNM-1907
http://forge.prestashop.com/browse/PNM-735
$error should be escaped, i.e:
```
{$error|escape:'htmlall':'UTF-8'}
```