Use -qq flag on apt-get to quiet installations of packages

plugins/nginx-vhosts/install

@@ -4,7 +4,7 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # latest stable NGINX 1.4.x with websocket support
 add-apt-repository -y ppa:nginx/stable
 apt-get update
-apt-get install -y nginx dnsutils
+apt-get install -qq -y nginx dnsutils
 
 if ! grep -q dokku-nginx-reload "/etc/sudoers"; then
   touch /etc/sudoers.tmp