Check if the script is running on a Debian-based system before starting

Fixed some spacing too

openvpn-install.sh

@@ -18,6 +18,12 @@ if [ ! -e /dev/net/tun ]; then
 fi
 
 
+if [ ! -e /etc/debian_version ]; then
+	echo "Looks like you aren't running this installer on a Debian-based system"
+	exit
+fi
+
+
 # Try to get our IP from the system and fallback to the Internet.
 # I do this to make the script compatible with NATed servers (lowendspirit.com)
 # and to avoid getting an IPv6.