Merge from head r253514,r253680,r253805,r254650:
  ---------------------------------------------------------------------
  r253514 | des | 2013-07-21 10:59:56 +0400 (вс, 21 июл 2013) | 5 lines

  Use the correct request syntax for proxied (tunneled) HTTPS requests.

  PR:             bin/180666
  MFC after:      3 days

  ---------------------------------------------------------------------
  r253680 | des | 2013-07-26 19:53:43 +0400 (пт, 26 июл 2013) | 7 lines

  Implement certificate verification, and many other SSL-related
  imrovements; complete details in the PR.

  PR:             kern/175514
  Submitted by:   Michael Gmelin <freebsd@grem.de>
  MFC after:      1 week

  ---------------------------------------------------------------------
  r253805 | des | 2013-07-30 17:07:55 +0400 (вт, 30 июл 2013) | 5 lines

  Include an Accept header in requests.

  PR:             kern/180917
  MFC after:      1 week

  ---------------------------------------------------------------------
  r254650 | des | 2013-08-22 11:43:36 +0400 (чт, 22 авг 2013) | 8 lines

  Even though it doesn't really make sense in the context of a CONNECT
  request, RFC 2616 14.23 mandates the presence of the Host: header in
  all HTTP 1.1 requests.

  PR:             kern/181445
  Submitted by:   Kimo <kimor79@yahoo.com>
  MFC after:      3 days

  ---------------------------------------------------------------------

Reviewed by:	des