Case C-560/13: Judgment of the Court (First Chamber) of 21 May 2015 (request for a preliminary ruling from the Bundesfinanzhof (Germany) — Finanzamt Ulm v Ingeborg Wagner-Raith (Reference for a preliminary ruling — Free movement of capital — Derogation — Movement of capital involving the provision of financial services — National legislation providing for flat-rate taxation of investment income from holdings in foreign investment funds — Black funds)