Bug 37197: Reports option to send to batch patron modification needs to use POST

Bug 37197: Reports option to send to batch patron modification needs to use POST

When you have an SQL report that selects cardnumber from borrowers, you
get a menuitem to send the results to Batch patron modification. Currently
that fails with a message about no card numbers or borrowernumbers given,
because it tries to do a GET with the op show, when modborrowers.pl is
expecting a POST with the op cud-show.

Test plan:
1. Without the patch, Reports - Create from SQL - name it and paste

select cardnumber from borrowers

   in the SQL textarea and save, then Run report.
2. Above the results is a "Batch operations with 20 visible records" menu,
   choose Batch patron modification
3. Note that instead of modifying the records, you're stuck with a message
   saying "No patron card numbers or borrowernumbers given." even though
   there's a whole string of them in the URL.
4. Apply patch, refresh the page with the results (oddly, no apparent need
   to even restart_all), and choose the menuitem again, but this time with
   a successful result.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>