Py3 upgrades to fundrawtransaction
Py3 upgrades to fundrawtransaction

Includes following commits from Bitcoin Core:
fa389d - [qa] Switch to py3
fac934 - [qa] Remove hardcoded "4 nodes" from test_framework

dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,bitcoinxt/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt