Add project validation tests.
Add project validation tests.

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