Fixes JavaScript of UserGroupOptionForm
Fixes JavaScript of UserGroupOptionForm

Previously, for an unchecked everybody user group checkbox, null was returned which caused, that no value for the everybody user group was submitted which causes an IllegalLinkException, since that value needs to exist.

PhrozenByte/WCF2,MeinAccount/WCF,PhrozenByte/WCF2,Morik/WCF,ramiusGitHub/WCF,WoltLab/WCF,Cyperghost/WCF,0xLeon/WCF,MeinAccount/WCF,NBZ4live/WCF,SoftCreatR/WCF,WoltLab/WCF,joshuaruesweg/WCF,SoftCreatR/WCF,ramiusGitHub/WCF,0xLeon/WCF,Morik/WCF,SoftCreatR/WCF,Morik/WCF,WoltLab/WCF,Cyperghost/WCF,0xLeon/WCF,WoltLab/WCF,joshuaruesweg/WCF,joshuaruesweg/WCF,Cyperghost/WCF,cashcat/WCF-1,Cyperghost/WCF,Cyperghost/WCF,Morik/WCF,SoftCreatR/WCF,MenesesEvandro/WCF,NBZ4live/WCF,MenesesEvandro/WCF,cashcat/WCF-1