Put back code mistakenly lost in rebase

Docker-DCO-1.1-Signed-off-by: Brad Murray <wyaeld@gmail.com> (github: wyaeld)
fix my own tests

Docker-DCO-1.1-Signed-off-by: Brad Murray <wyaeld@gmail.com> (github: wyae
add string.Trim to better handle .dockerignore contents

Docker-DCO-1.1-Signed-off-by: Brad Murray <wyaeld@gmail.com> (github: wyae