Demostrate how to build derived Nginx image(s) from Dockerfile(s).

Demostrate different behaviors while running Nginx with/without the "daemon off" flag.

Docker 1.5.0 or higher:

$ docker build  -f Dockerfile-daemon-off  .

Docker 1.4.1 or lower:

$ cp  Dockerfile-daemon-off  Dockerfile
$ docker build  .

Docker 1.5.0 or higher:

$ docker build  -f Dockerfile-daemonize  .

Docker 1.4.1 or lower:

$ cp  Dockerfile-daemonize  Dockerfile
$ docker build  .