Added tests for transaction.construct.
Added tests for transaction.construct.

coinwarp/dogeparty-lib,F483/counterparty-lib,jarymoth/counterpartyd,stefcrypto/counterparty-lib,tokenly/counterparty-lib,monaparty/counterparty-lib,CounterpartyXCP/counterparty-lib,monaparty/counterparty-lib,F483/counterparty-lib,gotcha/testcounter,CounterpartyXCP/counterparty-lib