* Feature: added `GuzzleHttp\json_encode` and `GuzzleHttp\json_decode`.
  https://github.com/guzzle/guzzle/pull/1389
* Bug fix: Fix sleep calculation when waiting for delayed requests.
  https://github.com/guzzle/guzzle/pull/1324
* Feature: More flexible history containers.
  https://github.com/guzzle/guzzle/pull/1373
* Bug fix: defer sink stream opening in StreamHandler.
  https://github.com/guzzle/guzzle/pull/1377
* Bug fix: do not attempt to escape cookie values.
  https://github.com/guzzle/guzzle/pull/1406
* Feature: report original content encoding and length on decoded responses.
  https://github.com/guzzle/guzzle/pull/1409
* Bug fix: rewind seekable request bodies before dispatching to cURL.
  https://github.com/guzzle/guzzle/pull/1422
* Bug fix: provide an empty string to `http_build_query` for HHVM workaround.
  https://github.com/guzzle/guzzle/pull/1367
