Move gradle signing code out of allprojects
Move gradle signing code out of allprojects

because it caused asking for the key passphrase multiple times, i.e. for
every subproject.

hy9902/Smack,lovely3x/Smack,andrey42/Smack,annovanvliet/Smack,TTalkIM/Smack,annovanvliet/Smack,magnetsystems/message-smack,dpr-odoo/Smack,deeringc/Smack,esl/Smack,Tibo-lg/Smack,xuIcream/Smack,ayne/Smack,vanitasvitae/Smack,qingsong-xu/Smack,u20024804/Smack,xuIcream/Smack,ishan1604/Smack,opg7371/Smack,chuangWu/Smack,Tibo-lg/Smack,vito-c/Smack,chuangWu/Smack,Flowdalic/Smack,ishan1604/Smack,vanitasvitae/Smack,dpr-odoo/Smack,kkroid/OnechatSmack,unisontech/Smack,opg7371/Smack,chuangWu/Smack,ishan1604/Smack,Flowdalic/Smack,u20024804/Smack,cjpx00008/Smack,u20024804/Smack,kkroid/OnechatSmack,hy9902/Smack,cjpx00008/Smack,igniterealtime/Smack,deeringc/Smack,igorexax3mal/Smack,vanitasvitae/Smack,opg7371/Smack,qingsong-xu/Smack,magnetsystems/message-smack,lovely3x/Smack,ayne/Smack,cjpx00008/Smack,qingsong-xu/Smack,andrey42/Smack,lovely3x/Smack,kkroid/OnechatSmack,hy9902/Smack,vanitasvitae/smack-omemo,mar-v-in/Smack,Tibo-lg/Smack,esl/Smack,Flowdalic/Smack,deeringc/Smack,igorexax3mal/Smack,mar-v-in/Smack,igniterealtime/Smack,andrey42/Smack,esl/Smack,xuIcream/Smack,unisontech/Smack,magnetsystems/message-smack,annovanvliet/Smack,dpr-odoo/Smack,vito-c/Smack,TTalkIM/Smack,mar-v-in/Smack,vanitasvitae/smack-omemo,vanitasvitae/smack-omemo,igorexax3mal/Smack,TTalkIM/Smack,igniterealtime/Smack,ayne/Smack,unisontech/Smack