DOC: More tweaks to postgres example.

examples/postgres/hub/Dockerfile

@@ -1,5 +1,7 @@
 FROM jupyter/jupyterhub
 
+MAINTAINER Jupyter Project <ipython-dev@scipy.org>
+
 RUN apt-get install -y libpq-dev \
     && apt-get autoremove -y \
     && apt-get clean -y \
@@ -7,3 +9,10 @@ RUN apt-get install -y libpq-dev \
 
 # Replace this with your own password.
 ENV JPY_PSQL_PASSWORD arglebargle
+
+RUN useradd -m -G shadow -p $(openssl passwd -1 rhea) rhea
+RUN chown rhea .
+
+RUN for name in io ganymede ; do useradd -m -p $(openssl passwd -1 $name) $name; done
+
+USER rhea