Sign function to send parameters to ledger

[canguruhh]

Send the transaction parameters to the ledger device and get the signed transaction after the user confirmed the transaction on the device.

[ehsueh]

Refer to issue #9 for initializing the device. For params, see examples in issues #2
to #7 or index.js at this repo

const transaction = await ledger.createPaymentTransactionNew(
        ledger_inputs,
        associatedKeysets,
        changePath,
        outputsScript,
        locktime,
        sigHash,
        segwit,
        initialTimestamp,
        additionals,
        expiryHeight,
        options
)