Fix sitemap for author permalink (#8585)
Fix sitemap for author permalink (#8585)

refs #8494
- include author in postgenerator for sitemap
ErisDS/Ghost,acburdine/Ghost,kevinansfield/Ghost,bitjson/Ghost,letsjustfixit/Ghost,letsjustfixit/Ghost,e10/Ghost,Gargol/Ghost,dbalders/Ghost,ErisDS/Ghost,sebgie/Ghost,dbalders/Ghost,TryGhost/Ghost,letsjustfixit/Ghost,JohnONolan/Ghost,janvt/Ghost,cwonrails/Ghost,TryGhost/Ghost,cwonrails/Ghost,mohanambati/Ghost,chevex/undoctrinate,kevinansfield/Ghost,JohnONolan/Ghost,acburdine/Ghost,BlueHatbRit/Ghost,Kikobeats/Ghost,acburdine/Ghost,janvt/Ghost,mohanambati/Ghost,sebgie/Ghost,e10/Ghost,JohnONolan/Ghost,kevinansfield/Ghost,Kikobeats/Ghost,Kikobeats/Ghost,BlueHatbRit/Ghost,cwonrails/Ghost,leninhasda/Ghost,sebgie/Ghost,Gargol/Ghost,bitjson/Ghost,ErisDS/Ghost,leninhasda/Ghost,TryGhost/Ghost,dbalders/Ghost,mohanambati/Ghost