Fixed the shirt color of the guards in Slaughterhouse heist. Now, instead of white shirts, the guards in the van wear red ones. The white color was correct for Payday: The Heist, because there the guards both in the van and inside the building wore white uniforms. However, in Payday 2, the guards inside the building are always in red uniforms, while the ones in the van were, for some reason, left with white shirts.