Fixed an issue with empty event tags still kept in the json output of the event index
Fixed an issue with empty event tags still kept in the json output of the event index

RichieB2B/MISP,RichieB2B/MISP,crruthe/MISP,crruthe/MISP,SteveClement/MISP,Rafiot/MISP,SteveClement/MISP,FIRSTdotorg/MISP,devnull-/MISP,MISP/MISP,TheDr1ver/MISP,MISP/MISP,MISP/MISP,TheDr1ver/MISP,FloatingGhost/MISP,TheDr1ver/MISP,cristianbell/MISP,FloatingGhost/MISP,Rafiot/MISP,devnull-/MISP,RichieB2B/MISP,crruthe/MISP,devnull-/MISP,Rafiot/MISP,TheDr1ver/MISP,FIRSTdotorg/MISP,RichieB2B/MISP,SteveClement/MISP,SteveClement/MISP,FloatingGhost/MISP,FloatingGhost/MISP,SteveClement/MISP,devnull-/MISP,crruthe/MISP,cristianbell/MISP,cristianbell/MISP,Rafiot/MISP,FIRSTdotorg/MISP,FIRSTdotorg/MISP,MISP/MISP,MISP/MISP,cristianbell/MISP