Add alex as devmapper and btrfs maintainer
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
add linked containers to hosts file

Docker-DCO-1.1-Signed-off-by: Bryan Murphy <bmurphy1976@gmail.com> (github: bmurphy1976)

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Tested-by: Solomon Hykes <solomon@docker.com> (github: shykes)