Add nginx official deb sources

nginx-setup.sh

apt-get install -y curl
# Install nginx
if [ "xx" = "x$(grep 'nginx' /etc/apt/sources.list )x" ] ; then
  echo 'Installing nginx...'
  echo '
# Repositories for up to date nginx packages
deb http://nginx.org/packages/mainline/ubuntu/ precise nginx
deb-src http://nginx.org/packages/mainline/ubuntu/ precise nginx' >> /etc/apt/sources.list
  curl -s http://nginx.org/keys/nginx_signing.key | apt-key add -
  apt-get update > /dev/null
  apt-get install -y nginx
fi