#2 Fix "Encapsulated" bug that causes "str" has no "group"

[Eric C. Jensen]

There's some sort of bug in parsing Encapsulated stuff
that causes 'exceptions.AttributeError: "str" object
has no attribute "group"' as referenced in
http://forums.devshed.com/archive/t-192002

I believe this fixes it.

[Eric C. Jensen]

patch to icap_handler.py

[Henrik Nordstrom]

Should find more robust way of parsing the header.