[imp] Fix for Headers.php with multiple http proxies

[Chuck Hagenbuch]

Quoting Michael M Slusarz <slusarz at bigworm.colorado.edu>:

> I would rather not put ISP specific code in IMP.  We can do a lot to
> attempt to figure out the true IP address, but there is no need to overdo
> it...

I agree with Michael, for what it's worth.

-chuck

--
Charles Hagenbuch, <chuck at horde.org>
must ... find ... acorns ... *thud*