Substitute HTTP Host header when proxying and fix HTTP socket reading.
Removed usage of requests config parameter that was removed.
Switched to using http_parser for parsing HTTP responses.
Additional HTTP fixes.

 * Fixed HTTP request parsing to get all data instead of only the first buffer
   worth.
 * Changed time.sleep(0) in get_data to wait_read to avoid endlessly looping.
 * Properly check for empty return value from socket.recv indicating the socket
   is closed.
Merge pull request #18 from jterrace/fix-http

Substitute HTTP Host header when proxying and fix HTTP socket reading.