Making it easier to represent parts of a message as a string
4.1.6 release
Merge branch 'develop'
Merge branch 'master' into develop
Merge tag 'guzzle-v4.1.6' into develop

Conflicts:
	CHANGELOG.md
	src/ClientInterface.php
	src/main/php/puzzle/message/AbstractMessage.php
	src/main/php/puzzle/message/Request.php
	src/test/php/message/AbstractMessageTest.php