s3 storage listobject bugs

[shijunLee]

while the s3 bucket have object like this

test-0.0.1.tgz
test/consul-0.0.1.tgz

user the S3Backend list object method test

func Test_ListObjects(t *testing.T) {
        backend := NewAmazonS3Backend("a-bucket-test", "", "ap-southeast-1", "s3-ap-southeast-1.amazonaws.com", "")
	objects, err := backend.ListObjects("test")
	if err != nil {
		fmt.Println(err)
		t.Fail()
	}
	for _, obj := range objects {
		fmt.Println(obj.Path)
	}
}

while get he file result

test-0.0.1.tgz
test/consul-0.0.1.tgz

while get the repo index.yaml, will get no such key error from s3, it while get file test/test-0.0.1.tgz, but this key is not exist