DSB is supported by the STFC grant ST/L000415/1 'String Theory, Gauge Theory and Duality'. CB is supported in part by the Belgian Federal Science Policy Office through the Interuniversity Attraction Pole P7/37 'Fundamental Interactions', and in part by the 'FWO-Vlaanderen' through the project G.0207.14N and by the Vrije Universiteit Brussel through the Strategic Research Program 'High-Energy Physics'. EM is supported by the ERC Advanced Grant "Strings and Gravity' (Grant No. 32004). FJR is supported by an STFC studentship
