support other netcodes in create_signed_tx
support other netcodes in create_signed_tx

mperklin/pycoin,richardkiss/pycoin,moocowmoo/pycoin,mperklin/pycoin,shivaenigma/pycoin,pycoin/pycoin,pycoin/pycoin,moocowmoo/pycoin,XertroV/pycoin,zsulocal/pycoin,XertroV/pycoin,zsulocal/pycoin,shivaenigma/pycoin,richardkiss/pycoin