Case C-218/10: Judgment of the Court (First Chamber) of 26 January 2012 (reference for a preliminary ruling from the Finanzgericht Hamburg — Germany) — ADV Allround Vermittlungs AG, in liquidation v Finanzamt Hamburg-Bergedorf (VAT — Sixth Directive — Articles 9, 17 and 18 — Determination of the place where services are supplied — Concept of ‘supply of staff’ — Self-employed persons — Need to ensure that a provision of services is assessed identically in relation to the provider and in relation to the recipient)