[Twisted-Python] HTTP updated

[Itamar Shtull-Trauring]

twisted's HTTP now does persistent and pipelined connections in HTTP/1.1 
(HTTP/1.0 is as before, with no support for persistent connections). If you 
set a content-length header, then data is sent as is, otherwise data is sent 
in chunked format.

Additional tests are probably needed.

What's left for full HTTP/1.1 support:
1. Ability for server to read chunked data.
2. 100 continue status (I wonder if anyone uses it)
3. universal content-range support

probably more stuff as well.