func (s *RepositoriesService) ListContributorsStats(owner, repo string) ([]ContributorStats, *Response, error) {
	u := fmt.Sprintf("repos/%v/%v/stats/contributors", owner, repo)
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return nil, nil, err
	}
	var contributorStats []ContributorStats
	resp, err := s.client.Do(req, &contributorStats)
	if err != nil {
		return nil, resp, err
	}
	return contributorStats, resp, err
}
ListContributorsStats gets a repo's contributor list with additions,
deletions and commit counts.

If this is the first time these statistics are requested for the given
repository, this method will return a non-nil error and a status code of
202. This is because this is the status that github returns to signify that
it is now computing the requested statistics. A follow up request, after a
delay of a second or so, should result in a successful request.

GitHub API Docs: https://developer.github.com/v3/repos/statistics/#contributors
package github
import (
	"fmt"
	"time"
)
type ContributorStats struct {
	Author *Contributor  `json:"author,omitempty"`
	Total  *int          `json:"total,omitempty"`
	Weeks  []WeeklyStats `json:"weeks,omitempty"`
}
func (c ContributorStats) String() string {
	return Stringify(c)
}
type WeeklyStats struct {
	Week      *Timestamp `json:"w,omitempty"`
	Additions *int       `json:"a,omitempty"`
	Deletions *int       `json:"d,omitempty"`
	Commits   *int       `json:"c,omitempty"`
}
func (w WeeklyStats) String() string {
	return Stringify(w)
}