Release 5.3.3

Tagged 6.3.3

Tagged 6.3.2

Tagged 6.3.1

Tagged 5.3.2

Tagged 6.3.0

Tagged 6.2.3

6.2.2 release

* Address HTTP_PROXY security vulnerability, CVE-2016-5385:

  https://httpoxy.org/
* Fixing timeout bug with StreamHandler:
  guzzle#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.

5.3.1 release