Update setup.py
Update setup.py

Adding more metadata to `setup.py`
karlfloersch/pyethereum,pipermerriam/pyethereum,ethermarket/pyethereum,ddworken/pyethereum,vaporry/pyethereum,inzem77/pyethereum,holiman/pyethereum,harlantwood/pyethereum,shahankhatch/pyethereum,pipermerriam/pyethereum,shahankhatch/pyethereum,ckeenan/pyethereum,karlfloersch/pyethereum,ethereum/pyethereum,jnnk/pyethereum,ethereum/pyethereum