Move back to NodeJS 4.x to support Ghost

...which does not run on NodeJS 5.x

user-data

@@ -1,10 +1,10 @@
 #!/bin/bash
 set -e -x
 
-# Add the NodeJS repository for 5.x
+# Add the NodeJS repository for 4.x
 # https://nodejs.org/en/download/package-manager/#debian-and-ubuntu-based-linux-distributions
 apt-get install -y curl
-curl -sL https://deb.nodesource.com/setup_5.x | bash -
+curl -sL https://deb.nodesource.com/setup_4.x | bash -
 
 # Upgrade the system without prompts
 # http://askubuntu.com/questions/146921/how-do-i-apt-get-y-dist-upgrade-without-a-grub-config-prompt