covnert TokenTimelock into initializers

contracts/mocks/TokenTimelockMock.sol

@@ -0,0 +1,14 @@
+pragma solidity ^0.4.24;
+
+import "../Initializable.sol";
+import "../token/ERC20/TokenTimelock.sol";
+
+contract TokenTimelockMock is Initializable, TokenTimelock {
+  constructor(
+    IERC20 token,
+    address beneficiary,
+    uint256 releaseTime
+  ) public {
+    TokenTimelock.initialize(token, beneficiary, releaseTime);
+  }
+}