CompleteMultipartUpload has x-amz-version-id missing in its response body

[ASHWIN A NAIR]

We found this bug where after we had created a multipart upload, uploaded parts and then completed a mpu, we have versionID missing from the response body of the complete multipart upload operation even when versioning is enabled for a bucket.

The following sequence of commands will illustrate the bug:

```
aws s3api create-multipart-upload --bucket testpart --key test.mp4
{
    "Bucket": "testpart",
    "Key": "test.mp4",
    "UploadId": "Y2Q3YjdiYWItOWE4YS00OWM3LWIxMWQtOWI4ODk2ODBkMTI0"
}

aws s3api upload-part --bucket testversion --key test.mp4 --part-number 1 --body ./test-parts/xaa --upload-id Y2Q3YjdiYWItOWE4YS00OWM3LWIxMWQtOWI4ODk2ODBkMTI0
{
    "ETag": "\"4051199a50475fc7750ba3a1ed68e6fd\""
}

aws s3api upload-part --bucket testversion --key test.mp4 --part-number 2 --body ./test-parts/xab --upload-id Y2Q3YjdiYWItOWE4YS00OWM3LWIxMWQtOWI4ODk2ODBkMTI0
{
    "ETag": "\"eee81eda7931a8678d99f6975e9d4809\""
}

aws s3api upload-part --bucket testversion --key test.mp4 --part-number 3 --body ./test-parts/xac --upload-id Y2Q3YjdiYWItOWE4YS00OWM3LWIxMWQtOWI4ODk2ODBkMTI0
{
    "ETag": "\"2589ea0b2337ee12eed8b048fe051849\""
}

aws s3api upload-part --bucket testversion --key test.mp4 --part-number 4 --body ./test-parts/xad --upload-id Y2Q3YjdiYWItOWE4YS00OWM3LWIxMWQtOWI4ODk2ODBkMTI0
{
    "ETag": "\"4f4caa01c98dfac4ee71796d67d890f4\""
}

aws s3api complete-multipart-upload --multipart-upload file://fileparts.json --bucket testversion --key test.mp4 --upload-id Y2Q3YjdiYWItOWE4YS00OWM3LWIxMWQtOWI4ODk2ODBkMTI0
{
    "Location": "http://saio:8080/testpart/test.mp4",
    "Bucket": "testpart",
    "Key": "test.mp4",
    "ETag": "\"63cbae132cd7b248ae57ae3ab6d16fc9-4\""
}

aws s3api get-bucket-versioning --bucket testversion
{
    "Status": "Enabled"
}
```