Bug 21943: Clean up holds template

Bug 21943: Clean up holds template

This patch makes a few markup corrections to the holds template in the
staff client: Replace some YUI markup with Bootstrap; Replace invalid
"alt" attributes with "title."

To test, apply the patch and test the process of placing a hold, both
single and multiple holds. At each step of the process the page should
look correct and adjust well at various browser widths.

Signed-off-by: Liz Rea <wizzyrea@gmail.com>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>