Do not use stdin for Dockerfiles.

See http://blog.mx17.net/2014/02/12/dockerfile-file-directory-error-using-add/

Suggested-by: Jesse Haubrich <jesse.haubrich@gmail.com>
chown on the Docker normal user.

Suggested-by: Jesse Haubrich <jesse.haubrich@gmail.com>
Merge pull request #21 from reproducible-research/jhaubrich-changes

Jhaubrich changes