fix thread safety issue and prevent importing keys to contact accounts
fix thread safety issue and prevent importing keys to contact accounts

RemitaBit/Remitabit,bitshares/bitshares-0.x,frrp/bitshares,Ziftr/bitshares,bitshares/bitshares-0.x,RemitaBit/Remitabit,RemitaBit/Remitabit,RemitaBit/Remitabit,bitshares/bitshares-0.x,frrp/bitshares,bitsuperlab/cpp-play,dacsunlimited/dac_play,frrp/bitshares,Ziftr/bitshares,camponez/bitshares,bitshares/bitshares,bitshares/devshares,bitshares/bitshares-0.x,FollowMyVote/bitshares,Ziftr/bitshares,FollowMyVote/bitshares,bitshares/bitshares-0.x,bitshares/bitshares,bitsuperlab/cpp-play,dacsunlimited/dac_play,jakeporter/Bitshares,dacsunlimited/dac_play,drltc/keyid,bitshares/devshares,RemitaBit/Remitabit,bitshares/devshares,camponez/bitshares,dacsunlimited/dac_play,FollowMyVote/bitshares,frrp/bitshares,bitshares/bitshares,bitsuperlab/cpp-play,jakeporter/Bitshares,drltc/keyid,bitsuperlab/cpp-play,bitsuperlab/cpp-play,bitsuperlab/cpp-play,bitshares/bitshares,dacsunlimited/dac_play,bitshares/bitshares,bitshares/devshares,bitshares/bitshares-0.x,Ziftr/bitshares,frrp/bitshares,dacsunlimited/dac_play,camponez/bitshares,camponez/bitshares,jakeporter/Bitshares,FollowMyVote/bitshares,bitshares/bitshares,camponez/bitshares,camponez/bitshares,drltc/keyid,bitshares/devshares,RemitaBit/Remitabit,jakeporter/Bitshares,bitshares/devshares,jakeporter/Bitshares,frrp/bitshares,jakeporter/Bitshares,FollowMyVote/bitshares,drltc/keyid,FollowMyVote/bitshares