Baloo overwrites `Transfer-Encoding` header

[jcoyne]

When I provide:

t.Post("/v1/identifiers/druids").
		SetHeader("Transfer-Encoding", "identity").
		Expect(t).
		Status(200).
		Type("json").
		JSON(map[string]string{"status": "OK"}).
		Done()

When I look at the packets (via wireshark) I see that my header has been overwritten by: Transfer-Encoding: chunked

[jcoyne]

It looks like I can work around this by adding:

		Body(nil).