convert SplitPayment to initializers

contracts/mocks/SplitPaymentMock.sol

+pragma solidity ^0.4.24;
+
+import "../Initializable.sol";
+import "../payment/SplitPayment.sol";
+
+contract SplitPaymentMock is Initializable, SplitPayment {
+  constructor(address[] payees, uint256[] shares) public {
+    SplitPayment.initialize(payees, shares);
+  }
+}

contracts/payment/SplitPayment.sol

 pragma solidity ^0.4.24;
 
+import "../Initializable.sol";
 import "../math/SafeMath.sol";
 
 
@@ -8,7 +9,7 @@ import "../math/SafeMath.sol";
  * @dev This contract can be used when payments need to be received by a group
  * of people and split proportionately to some number of shares they own.
  */
-contract SplitPayment {
+contract SplitPayment is Initializable {
   using SafeMath for uint256;
 
   uint256 private _totalShares = 0;
@@ -21,7 +22,7 @@ contract SplitPayment {
   /**
    * @dev Constructor
    */
-  constructor(address[] payees, uint256[] shares) public payable {
+  function initialize(address[] payees, uint256[] shares) public payable initializer {
     require(payees.length == shares.length);
     require(payees.length > 0);
 

test/payment/SplitPayment.test.js

@@ -8,7 +8,7 @@ require('chai')
 
 const { expectThrow } = require('../helpers/expectThrow');
 const { EVMRevert } = require('../helpers/EVMRevert.js');
-const SplitPayment = artifacts.require('SplitPayment');
+const SplitPayment = artifacts.require('SplitPaymentMock');
 
 contract('SplitPayment', function ([_, owner, payee1, payee2, payee3, nonpayee1, payer1]) {
   const amount = web3.toWei(1.0, 'ether');