func (r Repository) Exists(a model.Artifact) bool {
	repo := "releases"
	if a.IsSnapshot() {
		repo = "snapshots"
	}
	source := r.config.URL + filepath.Join(r.config.Path, repo, a.StorageLocation(r.settings.OS, a.AnyOS))
	model.Printf("%s", source)
	// TODO
	return false
}
func (r Repository) Fetch(a model.Artifact, destination string) error {
	repo := "releases"
	if a.IsSnapshot() {
		repo = "snapshots"
	}
	source := r.config.URL + filepath.Join(r.config.Path, repo, a.StorageLocation(r.settings.OS, a.AnyOS))
	model.Printf("downloading %s to %s\n", source, destination)
	sourceURL, err := url.Parse(source)
	if err != nil {
		return fmt.Errorf("invalid http request:%v", err)
	}
	sourceURL.User = url.UserPassword(r.config.User, r.config.Password)
	return transport.HttpGetFile(sourceURL.String(), destination)
}