api/volume.go
func volumePlansList(w http.ResponseWriter, r *http.Request, t auth.Token) error {
	contexts := permission.ContextsForPermission(t, permission.PermVolumeCreate)
	if len(contexts) == 0 {
		return permission.ErrUnauthorized
	}
	plansProvisioners, err := volume.ListPlans()
	if err != nil {
		return err
	}
	if len(plansProvisioners) == 0 {
		w.WriteHeader(http.StatusNoContent)
		return nil
	}
	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(plansProvisioners)
}
func volumePlansList(w http.ResponseWriter, r *http.Request, t auth.Token) error {
	contexts := permission.ContextsForPermission(t, permission.PermVolumeCreate)
	if len(contexts) == 0 {
		return permission.ErrUnauthorized
	}
	plansProvisioners, err := volume.ListPlans()
	if err != nil {
		return err
	}
	if len(plansProvisioners) == 0 {
		w.WriteHeader(http.StatusNoContent)
		return nil
	}
	w.Header().Set("Content-Type", "application/json")
	return json.NewEncoder(w).Encode(plansProvisioners)
}
// title: volume plan list
// path: /volumeplans
// method: GET
// produce: application/json
// responses:
//   200: List volume plans
//   401: Unauthorized