Bug 23273: Fix CSV export for overdues

Bug 23273: Fix CSV export for overdues

We should construct the URI parameters string manually to avoid
filtering problems.
We cannot send the full query_string to the template and expect that the
string will be escaped correctly.

Test plan:
- go to overdues.pl
- construct a search limiting by date due and library
- note number of overdues in results
- click "Download file of displayed overdues"
=> note that downloaded file contains just those in your search

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>