Return blank `Illuminate\Http\Response` (with `200` HTTP status) when `null` is returned from controller.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.0' into 2.1

Signed-off-by: crynobone <crynobone@gmail.com>

Conflicts:
	src/Orchestra/Resources/Response.php
	tests/ResponseTest.php