Fix nova_ssh container shell to allow instance resizes.

According to the configuration reference,
http://docs.openstack.org/mitaka/config-reference/compute/resize.html
When using KVM, nova utilizes SSH for instance resizing.
Kolla nova_ssh container has the nova user configured with "/sbin/nologin" shell,
which prevents nova_compute from successfully resizing instances.
Added fix to change shell from nologin to bash.

Change-Id: I46a48e242dae6ee6c9159bc30edd8b823ffbb515
Closes-Bug: 1617902

docker/nova/nova-ssh/Dockerfile.j2

@@ -16,6 +16,8 @@ RUN mkdir -p /var/run/sshd \
 
 {{ macros.install_packages(nova_ssh_packages | customizable("packages")) }}
 
+RUN chsh -s /bin/bash nova
+
 COPY extend_start.sh /usr/local/bin/kolla_extend_start
 RUN chmod 755 /usr/local/bin/kolla_extend_start