We should be explicit about supporting and testing support for these values being in a knife.rb file so they don't have to be specified every time, but still can be overridden by command line options. https://github.com/opscode/chef/commit/136ce0b0c9dff13e69e442f6c22b5edc71981c1c ([CHEF-3497](https://tickets.opscode.com/browse/CHEF-3497)) implemented this at the top level, so it should just work as long as we don't go poking around and try implementing our own logic (which is what we did previously).

It would be good to have a couple line refresher in the knife-openstack README that specifies how to do that, e.g.:

```
# Specifies that cloud instances be created and attached to the internet and admin networks, and bootstrapping via the internet network
knife[:network] = internet,admin

# Specifies to use the first network found alphabetically for bootstrapping cloud instances
knife[:network] = false
```