Use format as default format
Use format as default format

Use format form options as format if the format cannot be infered from the filename. 
ollietb/AvalancheImagineBundle,samrodriguez/AvalancheImagineBundle,0x2f8f/AvalancheImagineBundle,snpy/AvalancheImagineBundle,avalanche123/AvalancheImagineBundle,hephaistosthemaker/AvalancheImagineBundle,jmcclell/AvalancheImagineBundle,analogic/AvalancheImagineBundle