(2.6) webadmin: add select-all and deselect-all to PoolList and ActiveTransfer tables

Equivalent of http://rb.dcache.org/r/6164 for 2.6. Depends on pull request for fix/2.6/webadmin-submit-bug.

Target: 2.6
Require-notes: yes
Require-book: no
Feature-req: http://rt.dcache.org/Ticket/Display.html?id=8047

RELEASE NOTES:

Adds select/deselect all on lists on the Pool Usage and Active Transfer pages (when in authorized admin mode).
Merge pull request #260 from alrossi/feature/2.6/add-checkall-to-tables

Feature/2.6/add checkall to tables