Squid 3 HEAD - ICAP Modifications

Hi everyone,

Second try this time hopefully complete.

This is again patched against Squid 3 HEAD and includes 4 changes I would
like to have when working with webwasher/squid systems.

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
D.) When using X-Authenticated-User in C I need the username to be base64
encoded so I added another option to turn on encoding if needed.

Regards
Axel Westerhold