Using Burgomaster
Clarifying how the test server works. Closes #775
Ensuring the stream adapter does not add a default content-type
Adding automatic github releases
4.2.1 release
Merge branch 'develop'
Merge branch 'master' into develop
Merge tag 'guzzle-v4.2.1' into develop

Conflicts:
	CHANGELOG.md
	build/packager.php
	docs/testing.rst
	src/ClientInterface.php
	src/main/php/puzzle/adapter/StreamAdapter.php
	tests/Adapter/StreamAdapterTest.php