Bug 16310 - Remove the use of "onclick" from audio alerts template

Bug 16310 - Remove the use of "onclick" from audio alerts template

This patch removes one use of "onclick" in favor of defining events in
the JavaScript.

This patch also makes changes to the style of some buttons to make the
interface a little more consistent with current practices.

To test, apply the patch and go to Administration -> Audio alerts.

- In the list of existing audio alerts, click the "Edit" button for any
  alert. The correct data should be loaded in the edit form.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit fcd139b22239206142809993cf9e328a3cdce38d)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>