convert TimedCrowdsale to initializers

contracts/crowdsale/validation/TimedCrowdsale.sol

 pragma solidity ^0.4.24;
 
+import "../../Initializable.sol";
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 
@@ -8,7 +9,7 @@ import "../Crowdsale.sol";
  * @title TimedCrowdsale
  * @dev Crowdsale accepting contributions only within a time frame.
  */
-contract TimedCrowdsale is Crowdsale {
+contract TimedCrowdsale is Initializable, Crowdsale {
   using SafeMath for uint256;
 
   uint256 private _openingTime;
@@ -22,12 +23,15 @@ contract TimedCrowdsale is Crowdsale {
     _;
   }
 
+  constructor(uint256 openingTime, uint256 closingTime) public {
+  }
+
   /**
    * @dev Constructor, takes crowdsale opening and closing times.
    * @param openingTime Crowdsale opening time
    * @param closingTime Crowdsale closing time
    */
-  constructor(uint256 openingTime, uint256 closingTime) public {
+  function initialize(uint256 openingTime, uint256 closingTime) public initializer {
     // solium-disable-next-line security/no-block-members
     require(openingTime >= block.timestamp);
     require(closingTime >= openingTime);

contracts/mocks/TimedCrowdsaleImpl.sol

 pragma solidity ^0.4.24;
 
+import "../Initializable.sol";
 import "../token/ERC20/IERC20.sol";
 import "../crowdsale/validation/TimedCrowdsale.sol";
 
 
-contract TimedCrowdsaleImpl is TimedCrowdsale {
+contract TimedCrowdsaleImpl is Initializable, Crowdsale, TimedCrowdsale {
 
   constructor (
     uint256 openingTime,
@@ -17,6 +18,8 @@ contract TimedCrowdsaleImpl is TimedCrowdsale {
     Crowdsale(rate, wallet, token)
     TimedCrowdsale(openingTime, closingTime)
   {
+    Crowdsale.initialize(rate, wallet, token);
+    TimedCrowdsale.initialize(openingTime, closingTime);
   }
 
 }

test/crowdsale/TimedCrowdsale.test.js

@@ -12,7 +12,7 @@ require('chai')
   .should();
 
 const TimedCrowdsale = artifacts.require('TimedCrowdsaleImpl');
-const SimpleToken = artifacts.require('SimpleToken');
+const SimpleToken = artifacts.require('SimpleTokenMock');
 
 contract('TimedCrowdsale', function ([_, investor, wallet, purchaser]) {
   const rate = new BigNumber(1);