Document how to use GCE and OpenVPN with nogotofail.

This adds documentation and setup scripts for setting up nogotofail
MiTM on a Google Cloud Engine (GCE) VM instance through which traffic
is routed from client devices to the Internet. Traffic is routed from
clients to the GCE instance via an OpenVPN tunnel.

Fixes #3
Removed an accidental .bak file
Merge pull request #9 from klyubin/gce-openvpn-docs

Document how to use GCE and OpenVPN with nogotofail.