gapi: Add world interface and refactor existing code to use it

This is the initial base of what will hopefully become a powerful API
that machines will use to communicate. It will be the basis of the
stateful data store that can be used for exported resources, fact
exchange, state machine flags, locks, and much more.

yamlgraph/gapi.go

@@ -70,7 +70,7 @@ func (obj *GAPI) Graph() (*pgraph.Graph, error) {
 		return nil, fmt.Errorf("yamlgraph: ParseConfigFromFile returned nil")
 	}
 
-	g, err := config.NewGraphFromConfig(obj.data.Hostname, obj.data.EmbdEtcd, obj.data.Noop)
+	g, err := config.NewGraphFromConfig(obj.data.Hostname, obj.data.World, obj.data.Noop)
 	return g, err
 }