Correctly generate CONTAINER_NAME.

CONTAINER_NAME is not correctly generated which results in `link` command to fail.

```
-----> Linking postgres_djangompe:postgres with djangompe
docker inspect
postgres_djangompe

Usage: docker inspect CONTAINER|IMAGE [CONTAINER|IMAGE...]

Return low-level information on a container/image

  -f, --format="": Format the output using the given go template.

```