Bug 24518: Fix IE11 partner filtering

Bug 24518: Fix IE11 partner filtering

This patch adopts the approach detailed in comment #1.

It also fixes a couple of additional minor bugs relating to the ILL
partner list:
- Exclude partners with no email address, we cannot use them
- Quote the "value" attribute to avoid warnings displayed by IE, they
should be quoted anyway!

Test plan: USE IE11
- Apply the patch
- Define 3 ILL partner patrons (patrons in the category that has a code
that matches the <partner_code> value in the ILL config). One patron
should have no email address, the other two should have an email address
- Navigate to "Place request with partners" for an ILL request
- TEST: Observe that the patron with no email address is not displayed
- Try filtering the list
- TEST: Observe that the list filters correctly

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>