add: GetChain on local data
add: GetChain on local data

jnnk/pyethereum,ethereum/pyethereum,ethermarket/pyethereum,harlantwood/pyethereum,ckeenan/pyethereum,shahankhatch/pyethereum,ethers/pyethereum,karlfloersch/pyethereum,karlfloersch/pyethereum,inzem77/pyethereum,ethereum/pyethereum,ebuchman/daoist_protocol,ebuchman/daoist_protocol,ddworken/pyethereum,pipermerriam/pyethereum,vaporry/pyethereum,holiman/pyethereum,shahankhatch/pyethereum,pipermerriam/pyethereum