convert ERC721Mintable to initializers

contracts/mocks/ERC721MintableBurnableImpl.sol

 pragma solidity ^0.4.24;
 
+import "../Initializable.sol";
 import "../token/ERC721/ERC721Full.sol";
 import "../token/ERC721/ERC721Mintable.sol";
 import "../token/ERC721/ERC721Burnable.sol";
@@ -9,12 +10,12 @@ import "../token/ERC721/ERC721Burnable.sol";
  * @title ERC721MintableBurnableImpl
  */
 contract ERC721MintableBurnableImpl
-  is ERC721Full, ERC721Mintable, ERC721Burnable {
+  is Initializable, ERC721Full, ERC721Mintable, ERC721Burnable {
 
   constructor()
-    ERC721Mintable()
-    ERC721Full("Test", "TEST")
     public
   {
+    ERC721Full.initialize("Test", "TEST");
+    ERC721Mintable.initialize();
   }
 }

contracts/token/ERC721/ERC721Mintable.sol

 pragma solidity ^0.4.24;
 
+import "../../Initializable.sol";
 import "./ERC721Full.sol";
 import "../../access/roles/MinterRole.sol";
 
@@ -8,7 +9,7 @@ import "../../access/roles/MinterRole.sol";
  * @title ERC721Mintable
  * @dev ERC721 minting logic
  */
-contract ERC721Mintable is ERC721Full, MinterRole {
+contract ERC721Mintable is Initializable, ERC721Full, MinterRole {
   event MintingFinished();
 
   bool private _mintingFinished = false;
@@ -18,6 +19,10 @@ contract ERC721Mintable is ERC721Full, MinterRole {
     _;
   }
 
+  function initialize() public initializer {
+    MinterRole.initialize();
+  }
+
   /**
    * @return true if the minting is finished.
    */