message: if an unspent is pruned, the reason and pruning details are logged
  Summary:
  Reviewers: zacleids, mark
  Subscribers: ben
diff: @@ -378,13 +378,34 @@ exports.createTransaction = function(params) {
  minInputValue = params.minUnspentSize;
  }
  + let prunedUnspentCount = 0;
  + const originalUnspentCount = unspents.length;
  unspents = _.filter(unspents, function(unspent) {
  const isSegwitInput = !!unspent.witnessScript;
  const currentInputSize = isSegwitInput ? P2SH_P2WSH_INPUT_SIZE : P2SH_INPUT_SIZE;
  - const currentMinInputValue = Math.max(minInputValue, (feeRate * currentInputSize) / 1000);
  - return unspent.value > currentMinInputValue;
  + const feeBasedMinInputValue = (feeRate * currentInputSize) / 1000;
  + const currentMinInputValue = Math.max(minInputValue, feeBasedMinInputValue);
  + if (currentMinInputValue > unspent.value || true) {
  + // pruning unspent
  + const pruneDetails = {
  + generalMinInputValue: minInputValue,
  + feeBasedMinInputValue,
  + currentMinInputValue,
  + feeRate,
  + inputSize: currentInputSize,
  + unspent: unspent
  + };
  + console.log(`pruning unspent: ${JSON.stringify(pruneDetails, null, 4)}`);
  + prunedUnspentCount++;
  + return false;
  + }
  + return true;
  });
  + if (prunedUnspentCount > 0) {
  + console.log(`pruned ${prunedUnspentCount} out of ${originalUnspentCount} unspents`);
  + }
  +
  if (unspents.length === 0) {
  throw new Error('insufficient funds');
  }
  