Merge from vendor branch TNF:

Merge from vendor branch TNF:
Imporging www/ruby-net-http-persistent package version 1.8.1.

Manages persistent connections using Net::HTTP plus a speed fix for 1.8.
It's thread-safe too!

Using persistent HTTP connections can dramatically increase the speed of
HTTP.  Creating a new HTTP connection for every request involves an extra
TCP round-trip and causes TCP congestion avoidance negotiation to start
over.

Net::HTTP supports persistent connections with some API methods but does not
handle reconnection gracefully.  net-http-persistent supports reconnection
according to RFC 2616.