(2.6) webadmin: fix regressions in PoolList and ActiveTransfers blocking command submission

This patch combines the fixes from patches 6061 and 6062, adapted to these pages which do not have auto-refresh.

See http://rb.dcache.org/r/6161 and http://rb.dcache.org/r/6162 for details.

Target: 2.6
Require-notes: yes
Require-book: no

Testing done:

As with the patches for master.
Merge pull request #259 from alrossi/fix/2.6/webadmin-submit-bug

(2.6) webadmin: fix regressions in PoolList and ActiveTransfers blocking...