Fix fedcloud export get script
Fix fedcloud export get script

 - skip users with no certificates

Laliska/perun-services,frhrdina/perun-services,CESNET/perun-services,zlamalp/perun-services,stavamichal/perun-services,zlamalp/perun-services,CESNET/perun-services,CESNET/perun-services,sustr4/perun-services,zlamalp/perun-services,CESNET/perun-services,Laliska/perun-services,frhrdina/perun-services,stavamichal/perun-services,stavamichal/perun-services,sustr4/perun-services,Laliska/perun-services,Laliska/perun-services,sustr4/perun-services,frhrdina/perun-services,zlamalp/perun-services,frhrdina/perun-services,stavamichal/perun-services,sustr4/perun-services