fix content-type for job.Stdout.Add

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
fix content-type for legacy

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
Fix regression with ADD of tar files
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Mount-bind the PTY as container console - allow for tmux/screen to run

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)
Merge pull request #4128 from vieux/fix_header_content-type_api

Fix header content type api
Merge pull request #4134 from crosbymichael/fix-add-magic-regression

Fix regression with ADD of tar files
Merge pull request #4135 from creack/console_support

Mount-bind the PTY as container console - allow for tmux/screen to run