[pca] password protecting the proxy server

[amy.rich at tufts.edu]

I've set up pca as a proxy server, and that's working fine.  Based on the
documentation, though, there doesn't appear to be a way to password protect
the proxy server.  I don't want to expose my SOA password to everyone with
access to port 80.  I also don't want to become a patch repository for anyone
who knows the host exists.

Is there some "proxy username" and "proxy password" setting that I've missed
to do something like simple .htaccess authenticantion for each node to talk to
the proxy?

Thanks...