* Address HTTP_PROXY security vulnerability, CVE-2016-5385:
  https://httpoxy.org/
* Fixing timeout bug with StreamHandler:
  https://github.com/guzzle/guzzle/pull/1488
* Only read up to `Content-Length` in PHP StreamHandler to avoid timeouts when
  a server does not honor `Connection: close`.
* Ignore URI fragment when sending requests.
