Make network config use  vcloud-edgegateway tools

Rather than continue to use `vcloud-net-spinner`, we should be looking to use
the
[`alphagov/vcloud-edgegateway`](https://github.com/alphagov/vcloud-edgegateway)
tool.

This means that we can specify our firewall configuration in one YAML file. This
commit adds that YAML file. It worked fine during testing.
Add vcloud provisioning tools to Gemfile
YAML files
Add bootstrap to `common` directory
Add Org vDC network configuration