Expose the locales in Dockerfile

While the locales are generated with locale-gen, this does not enforce
the en_US.UTF-8 locale inside the container.

See the following links for more information:

- https://github.com/docker/docker/issues/2424
- http://jaredmarkell.com/docker-and-locales/

image/Dockerfile

@@ -9,4 +9,8 @@ RUN /bd_build/prepare.sh && \
 	/bd_build/fix_pam_bug.sh && \
 	/bd_build/cleanup.sh
 
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
 CMD ["/sbin/my_init"]