nginx repo is no longer needed

Author: cbbs

Dockerfile

@@ -9,7 +9,6 @@ FROM dockerfile/ubuntu
 
 # Install Nginx.
 RUN \
- add-apt-repository -y ppa:nginx/stable && \
  apt-get update && \
  apt-get install -y nginx && \
  rm -rf /var/lib/apt/lists/* && \