message: add signature field on TransferTransaction
diff: @@ -12,6 +12,7 @@ export class TransferBuilder {
  private _data: string;
  private _signKey: string;
  private _expirationTime: number;
  + private _signature: string;
  //initialize with default values for non mandatory fields
  constructor() {
  @@ -54,14 +55,14 @@ export class TransferBuilder {
  signAndBuild(): string {
  if (this.hasMandatoryFields()) {
  - const signature = this.ethSignMsgHash();
  + this.ethSignMsgHash();
  return sendMultiSigData(
  this._toAddress,
  new BigNumber(this._amount).toNumber(),
  this._data,
  this._expirationTime,
  this._sequenceId,
  - signature,
  + this._signature,
  );
  }
  throw new BuildTransactionError(
  @@ -102,7 +103,7 @@ export class TransferBuilder {
  ];
  }
  - private ethSignMsgHash(): string {
  + private ethSignMsgHash(): void {
  const data = ethUtil.bufferToHex(EthereumAbi.soliditySHA3(...this.getSHA()));
  const signatureInParts = ethUtil.ecsign(
  new Buffer(ethUtil.stripHexPrefix(data), 'hex'),
  @@ -115,6 +116,6 @@ export class TransferBuilder {
  const v = ethUtil.stripHexPrefix(ethUtil.intToHex(signatureInParts.v));
  // Concatenate the r, s and v parts to make the signature string
  - return ethUtil.addHexPrefix(r.concat(s, v));
  + this._signature = ethUtil.addHexPrefix(r.concat(s, v));
  }
  }
  