libecap v0.2.0 options support: supply client IP and user name to eCAP.

libecap v0.2.0 options support: supply client IP and user name to eCAP.

Squid now uses libecap::Options API to send client IP and user name
meta-information to the eCAP adapter transaction, just like ICAP code
does when talking to an ICAP service transaction.

Renamed related icap_* options to their more general adaptation_*
equivalents because they now control both eCAP and ICAP behavior.
Old icap_* names are deprecated but still available.

Converted eCAP service configuration code to support the new Options
API, polished.