added Gatekeeper mention to changelog
added Gatekeeper mention to changelog

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