ListCommits and ListFiles should return slices, not pointers

ref: #130

github/pulls.go

@@ -148,7 +148,7 @@ func (s *PullRequestsService) Edit(owner string, repo string, number int, pull *
 // ListCommits lists the commits in a pull request.
 //
 // GitHub API docs: https://developer.github.com/v3/pulls/#list-commits-on-a-pull-request
-func (s *PullRequestsService) ListCommits(owner string, repo string, number int, opt *ListOptions) (*[]Commit, *Response, error) {
+func (s *PullRequestsService) ListCommits(owner string, repo string, number int, opt *ListOptions) ([]Commit, *Response, error) {
 	u := fmt.Sprintf("repos/%v/%v/pulls/%d/commits", owner, repo, number)
 	u, err := addOptions(u, opt)
 	if err != nil {
@@ -166,13 +166,13 @@ func (s *PullRequestsService) ListCommits(owner string, repo string, number int,
 		return nil, resp, err
 	}
 
-	return commits, resp, err
+	return *commits, resp, err
 }
 
 // ListFiles lists the files in a pull request.
 //
 // GitHub API docs: https://developer.github.com/v3/pulls/#list-pull-requests-files
-func (s *PullRequestsService) ListFiles(owner string, repo string, number int, opt *ListOptions) (*[]CommitFile, *Response, error) {
+func (s *PullRequestsService) ListFiles(owner string, repo string, number int, opt *ListOptions) ([]CommitFile, *Response, error) {
 	u := fmt.Sprintf("repos/%v/%v/pulls/%d/files", owner, repo, number)
 	u, err := addOptions(u, opt)
 	if err != nil {
@@ -190,7 +190,7 @@ func (s *PullRequestsService) ListFiles(owner string, repo string, number int, o
 		return nil, resp, err
 	}
 
-	return commitFiles, resp, err
+	return *commitFiles, resp, err
 }
 
 // IsMerged checks if a pull request has been merged.

github/pulls_test.go

@@ -174,7 +174,7 @@ func TestPullRequestsService_ListCommits(t *testing.T) {
 		t.Errorf("PullRequests.ListCommits returned error: %v", err)
 	}
 
-	want := &[]Commit{
+	want := []Commit{
 		Commit{
 			SHA: String("3"),
 			Parents: []Commit{
@@ -233,7 +233,7 @@ func TestPullRequestsService_ListFiles(t *testing.T) {
 		t.Errorf("PullRequests.ListFiles returned error: %v", err)
 	}
 
-	want := &[]CommitFile{
+	want := []CommitFile{
 		CommitFile{
 			SHA:       String("6dcb09b5b57875f334f61aebed695e2e4193db5e"),
 			Filename:  String("file1.txt"),