Allow to pass additional arguments to Batch.complete()

We hit an issue on Nuxeo Drive with big uploads using S3:

• chunks uploads were OK
• upload completion on Amazon side was OK
• but upload on the Nuxeo side was NOT GOOD because of a timeout.

So to fix it, we should allow to pass additional arguments to the Batch.complete() method in order to set custom timeouts from outside the client, for example.