podman build prints image ID twice

In current master, podman-build prints the image ID twice.


```
$ cat Dockerfile
FROM alpine
RUN echo "Hello World"

$ ~/containers/libpod/bin/podman build .
STEP 1: FROM alpine
STEP 2: RUN echo "Hello World"
Hello World
STEP 3: COMMIT
a2d3a36dd04da5155000350e74d5d975e008abe611e2f67082b1c9b25477dbaf
a2d3a36dd04da5155000350e74d5d975e008abe611e2f67082b1c9b25477dbaf
```