convert ConditionalEscrow to initializers

contracts/mocks/ConditionalEscrowMock.sol

@@ -1,13 +1,18 @@
 pragma solidity ^0.4.24;
 
 
+import "../Initializable.sol";
 import "../payment/ConditionalEscrow.sol";
 
 
 // mock class using ConditionalEscrow
-contract ConditionalEscrowMock is ConditionalEscrow {
+contract ConditionalEscrowMock is Initializable, ConditionalEscrow {
   mapping(address => bool) private _allowed;
 
+  constructor() public {
+    ConditionalEscrow.initialize();
+  }
+
   function setAllowed(address payee, bool allowed) public {
     _allowed[payee] = allowed;
   }