Don't force srs for any file extension. Refs #832.
Don't force srs for any file extension. Refs #832.

We can no longer assume the file extension will be entered into this
field.

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