Bug 15858: Use Font Awesome icons in dialog alert for addorder.tt

Bug 15858: Use Font Awesome icons in dialog alert for addorder.tt

A warning is raised when order amount exceed budget or fund this dialog needs to be styled with Font Awesome icons.

To test:
-Add orders to a basket
-Exceed a fund or budget
-Notice about the dialog alert
-Apply patch
-Exceed again and see the new icons

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com