Added 'gmagick' as a valid driver in configuration
Added 'gmagick' as a valid driver in configuration

samrodriguez/AvalancheImagineBundle,avalanche123/AvalancheImagineBundle,analogic/AvalancheImagineBundle,0x2f8f/AvalancheImagineBundle,hephaistosthemaker/AvalancheImagineBundle,ollietb/AvalancheImagineBundle,jmcclell/AvalancheImagineBundle,snpy/AvalancheImagineBundle