dcache-webadmin: add autorefresh to appropriate pages

Adds Ajax auto refresh behavior to appropriate webadmin pages.

This entails the addition of a few shared protected methods, and the adjusting of markup accordingly.

Testing:

Redeployed and observed changes effected through admin service.

Target: master
Patch: http://rb.dcache.org/r/6085/
Require-notes: yes
Require-book: no
Acked-by: Tigran

RELEASE NOTES
CellServices, PoolQueues, PoolGroups, Active and Tape transfer pages now autorefresh, in addition to Alarms, Billing and PoolQueue plots.