Restored chunk delimiters to chunked response received by Zend\H...

Fix for issues #3036 and #3267.

Issue #3036 was raised (and "fixed" by PR #3169) because of a misunderstanding of the proper use of `Zend\Http\Response::getContent()`.  PR #3169 broke `Zend\Http\Response::getBody()` (when used with `Zend\Http\Client\Adapter\Socket`) by decoding chunked responses when it shouldn't have.

The proper resolution for issue #3036 should have been to recommend use of `Zend\Http\Response::getBody()` instead of `Zend\Http\Response::getContent()`.