Log Message:
py-autobahn: updated to 19.8.1

19.8.1
new: implement XBR off-chain delegate transaction signing and verification
new: update XBR for new contract ABIs

19.7.2
fix: monkey patch re-add removed helper functions removed in eth-abi
new: simple blockchain (XBR) client
new: update XBR ABI files
new: XBR endpoint transaction signing
new: client side catching of WAMP URI errors in \ 
session.call|register|publish|subscribe