fix author join for federation callbacks with Poll
fix author join for federation callbacks with Poll

spixi/diaspora,Amadren/diaspora,Muhannes/diaspora,KentShikama/diaspora,jhass/diaspora,geraspora/diaspora,spixi/diaspora,SuperTux88/diaspora,Flaburgan/diaspora,jhass/diaspora,Amadren/diaspora,geraspora/diaspora,KentShikama/diaspora,despora/diaspora,KentShikama/diaspora,spixi/diaspora,jhass/diaspora,Flaburgan/diaspora,SuperTux88/diaspora,despora/diaspora,Flaburgan/diaspora,Muhannes/diaspora,Flaburgan/diaspora,diaspora/diaspora,Amadren/diaspora,despora/diaspora,SuperTux88/diaspora,KentShikama/diaspora,geraspora/diaspora,SuperTux88/diaspora,jhass/diaspora,Muhannes/diaspora,diaspora/diaspora,diaspora/diaspora,despora/diaspora,geraspora/diaspora,Amadren/diaspora,spixi/diaspora,Muhannes/diaspora,diaspora/diaspora