Remove raw file logic from directory provider and allow formats that we plan to support.
Remove raw file logic from directory provider and allow formats that we plan to support.

Zhao-Qi/tilemill,MappingKat/tilemill,fxtentacle/tilemill,florianf/tileoven,makinacorpus/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,mbrukman/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,tizzybec/tilemill,nyimbi/tilemill,fxtentacle/tilemill,paulovieira/tilemill-clima,MappingKat/tilemill,florianf/tileoven,tilemill-project/tilemill,nyimbi/tilemill,mbrukman/tilemill,MappingKat/tilemill,tizzybec/tilemill,paulovieira/tilemill-clima,Teino1978-Corp/Teino1978-Corp-tilemill,MappingKat/tilemill,nyimbi/tilemill,mbrukman/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,mbrukman/tilemill,mbrukman/tilemill,tilemill-project/tilemill,fxtentacle/tilemill,tilemill-project/tilemill,florianf/tileoven,Zhao-Qi/tilemill,Teino1978-Corp/Teino1978-Corp-tilemill,paulovieira/tilemill-clima,Zhao-Qi/tilemill,MappingKat/tilemill,isaacs/tilemill,Zhao-Qi/tilemill,tizzybec/tilemill,isaacs/tilemill,nyimbi/tilemill,makinacorpus/tilemill,paulovieira/tilemill-clima,Zhao-Qi/tilemill,fxtentacle/tilemill,fxtentacle/tilemill,tizzybec/tilemill,nyimbi/tilemill,isaacs/tilemill,tizzybec/tilemill,paulovieira/tilemill-clima