Making a snapshot for older version 0.9.6

dockerfile/Dockerfile

-FROM debian:stretch
+FROM debian:jessie
 
 LABEL Description=DaCHS\ is\ a\ publishing\ infrastructure\ for\ the\ Virtual\ Observatory. \
       Author=Markus\ Demleitner \
@@ -12,16 +12,18 @@ RUN DEBIAN_FRONTEND='noninteractive'               && \
     apt-get install -y sudo wget vim locales git gnupg  && \
     apt-get clean
 
-ENV LANG C.UTF-8
+ENV LANG=C.UTF-8
 RUN echo LANG="$LANG" > /etc/default/locale
 
-RUN echo 'deb http://vo.ari.uni-heidelberg.de/debian release main'  \
+ENV PG_VERSION=9.4
+
+RUN echo 'deb http://vo.ari.uni-heidelberg.de/debian stable main'   \
         > /etc/apt/sources.list.d/gavo.list                         && \
     wget -qO - http://docs.g-vo.org/archive-key.asc | apt-key add -
 
 RUN DEBIAN_FRONTEND='noninteractive'                                  && \
     apt-get update                                                    && \
-    apt-get install -y python-gavodachs postgresql-9.6-q3c  && \
+    apt-get install -y python-gavodachs postgresql-${PG_VERSION}-q3c  && \
     apt-get clean
 
 ENV GAVO_ROOT="/var/gavo"                       \