Development: Update Dockerfile and create possibility to run local cluster

To help in developing features, the Dockerfile and its entrypoint have been extended.
The README.md explains stuff in detail, in short:

- you can now run a Patroni cluster with a single command

Dockerfile

@@ -13,23 +13,23 @@ RUN apt-get update -y
 RUN apt-get upgrade -y
 
 ENV PGVERSION 9.4
-RUN apt-get install python python-psycopg2 python-yaml python-requests python-boto postgresql-${PGVERSION} python-dnspython python-pip -y
-RUN pip install zake
+RUN apt-get install python python-psycopg2 python-yaml python-requests python-boto postgresql-${PGVERSION} python-dnspython python-kazoo -y
 
 ENV PATH /usr/lib/postgresql/${PGVERSION}/bin:$PATH
 
 RUN mkdir -p /patroni/helpers
 ADD patroni.py /patroni/patroni.py
 ADD helpers /patroni/helpers
-ADD postgres0.yml /patroni/
 
-ENV ETCDVERSION 2.0.12
+ENV ETCDVERSION 2.0.13
 RUN curl -L https://github.com/coreos/etcd/releases/download/v${ETCDVERSION}/etcd-v${ETCDVERSION}-linux-amd64.tar.gz | tar xz -C /bin --strip=1 --wildcards --no-anchored etcd etcdctl
 
 ## Setting up a simple script that will serve as an entrypoint
-RUN mkdir /data/ && touch /var/log/etcd.log /var/log/etcd.err && chown postgres:postgres /var/log/etcd.*
-RUN chown postgres:postgres -R /patroni/ /data/
-ADD entrypoint.sh /entrypoint.sh
+RUN mkdir /data/ && touch /var/log/etcd.log /var/log/etcd.err /pgpass /patroni/postgres.yml
+RUN chown postgres:postgres -R /patroni/ /data/ /pgpass /var/log/etcd.* /patroni/postgres.yml
+ADD docker/entrypoint.sh /entrypoint.sh
+
+EXPOSE 4001 5432 2380
 
 ENTRYPOINT ["/bin/bash", "/entrypoint.sh"]
 USER postgres