Fix bug where updated DB version causes crash on restart
Fix bug where updated DB version causes crash on restart

cryptonomex/graphene,bigoc/openchain,bigoc/openchain,peertracksinc/muse,abitmore/bitshares-2,abitmore/bitshares-2,pmconrad/graphene,oxarbitrage/bitshares-core,pmconrad/graphene,bitsuperlab/cpp-play2,bitshares/bitshares-2,peertracksinc/muse,peertracksinc/muse,cryptonomex/graphene,cryptonomex/graphene,pmconrad/graphene,bitshares/bitshares-2,bigoc/openchain,bigoc/openchain,bitshares/bitshares-2,oxarbitrage/bitshares-core,abitmore/bitshares-2,peertracksinc/muse,pmconrad/graphene,bitsuperlab/cpp-play2,bitsuperlab/cpp-play2,oxarbitrage/bitshares-core,oxarbitrage/bitshares-core,abitmore/bitshares-2,bitshares/bitshares-2