Minor fix: Adds missing comma in composer.json (was broken)
Minor fix: Adds missing comma in composer.json (was broken)

micaherne/installers,bluematt/composer-installers,ribrit/installers,beaver-dev/feather-installers,dedalozzo/installers,potherca-contrib/installers,corneltek/installers,c9s/installers,KennisMeester/installers,blesta/installers,kidaa/installers,buildsample/installers,composer/installers,shipci/installers