Modifications to the ICAP client I would like to see

Hi everyone,

attached you'll find 3 modifications against HEAD I would like to have:

A.) ICAPServiceRep::TheSessionFailureLimit set through squid.conf
B.) ICAPServiceRep delay for a down service set through squid.conf
C.) Instead of hardcoding the Header used to transfer the username being
able to set the used one through squid.conf

I tested the patch the best I could. The defaults are as hardcoded before. A
simple web poligraph test did not show any problems.

Regards,
Axel Westerhold