Revert "Change content-type for json stream to application/x-json-stream."

This reverts commit 10ab2089ce189d5bea3f7aaac3b5081471309478.

Conflicts:
	api/client/utils.go
	docs/sources/reference/api/docker_remote_api.md

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Revert "Fix line delimited JSON response"

This reverts commit d2f75a3040e72562ffa825d5c3efa7004af2640a.

Conflicts:
	integration-cli/docker_api_events_test.go

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)