fix: the travis image is linked to pyethereum from brainbot-com
fix: the travis image is linked to pyethereum from brainbot-com

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