Change base image to ubuntu xenial for Plus controller

Author: pleshakov

nginx-plus-controller/Dockerfile

@@ -1,19 +1,18 @@
-FROM ubuntu:14.04
+FROM ubuntu:16.04
 
 MAINTAINER NGINX Docker Maintainers "[email protected]"
 
 # Set the debconf front end to Noninteractive
 RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections
 
-RUN apt-get update && apt-get install -y -q wget apt-transport-https
+RUN apt-get update && apt-get install -y -q wget lsb-release apt-transport-https
 
 # Download certificate and key from the customer portal (https://cs.nginx.com)
 # and copy to the build context
 ADD nginx-repo.crt /etc/ssl/nginx/
 ADD nginx-repo.key /etc/ssl/nginx/
 
 # Get other files required for installation
-RUN wget -q -O /etc/ssl/nginx/CA.crt https://cs.nginx.com/static/files/CA.crt
 RUN wget -q -O - http://nginx.org/keys/nginx_signing.key | apt-key add -
 RUN wget -q -O /etc/apt/apt.conf.d/90nginx https://cs.nginx.com/static/files/90nginx