json: cannot unmarshal number into Go struct field Segment.segments.id of type string

[Alex Flint]

Looks like mailchimp API is serving integer tag IDs, and gochimp3 is using strings to represent tag IDs. To reproduce:

	mailchimp := gochimp3.New(os.Getenv("MAILCHIMP_API_KEY"))

	list, err := mailchimp.GetList(mailchimpAudienceID, nil)
	if err != nil {
		return err
	}

	segments, err := list.GetSegments(&gochimp3.SegmentQueryParams{})
	if err != nil {
		return err
	}

	for _, seg := range segments.Segments {
		log.Println(seg.ID, seg.Name)
	}
	return nil

Output is:

json: cannot unmarshal number into Go struct field Segment.segments.id of type string