Docker-builder should use dockerfile directory and not top level as build context

[rafecolton]

Consider the following .docker/ directory that exists in the project top level:

.docker
└── nginx
    ├── 001-default
    ├── Dockerfile
    ├── nginx-wrapper
    └── nginx.conf

When running docker-builder from the top level, to ADD the nginx.conf file should be:

ADD nginx.conf /etc/nginx/nginx.conf

Instead, only the following line works:

ADD .docker/nginx/nginx.conf /etc/nginx/nginx.conf

This means that docker-builder is using the top level directory as the context instead of the .docker/nginx/ directory (the one that contains the Dockerfile) as it should.

[rafecolton]

Fixed.