Request update option for GCE installs that doesn't generate a new openVPN file

[Michael Kennedy]

I noticed when updating GCE instances of ngtf the script generates new openvpn keys/file (using the setup.sh script) - it's a little inconvenient exporting a new openvpn file to the device. I personally would prefer if there was an update option that didn't generate a new openvpn keys/file.