change store::on_gossip_attestation to take a ref to signed attestations#278

MegaRedHand merged 3 commits intolambdaclass:mainlambdaclass/ethlambda:mainfrom

d4m014:refactor/gossip-attestation-by-refd4m014/ethlambda:refactor/gossip-attestation-by-refCopy head branch name to clipboard