Base all on xenial to save some space loading chunks, clean-up images

data/Dockerfiles/pdns/Dockerfile

@@ -1,9 +1,15 @@
-FROM debian:jessie
+FROM ubuntu:xenial
 MAINTAINER Andre Peters <andre.peters@debinux.de>
 
 ENV DEBIAN_FRONTEND noninteractive
+ENV LC_ALL C
 
-RUN echo 'deb http://repo.powerdns.com/debian jessie-rec-40 main' > /etc/apt/sources.list.d/pdns.list
+RUN dpkg-divert --local --rename --add /sbin/initctl \
+    && ln -sf /bin/true /sbin/initctl \
+    && dpkg-divert --local --rename --add /usr/bin/ischroot \
+    && ln -sf /bin/true /usr/bin/ischroot
+
+RUN echo 'deb http://repo.powerdns.com/ubuntu xenial-rec-40 main' > /etc/apt/sources.list.d/pdns.list
 
 RUN echo 'Package: pdns-*\n\
 Pin: origin repo.powerdns.com\n\
@@ -16,3 +22,5 @@ RUN apt-key adv --fetch-keys http://repo.powerdns.com/FD380FBB-pub.asc \
 CMD ["/usr/sbin/pdns_recursor"]
 
 EXPOSE 53/udp
+
+RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*