remove unnecessary sender arguments

contracts/mocks/ERC721TokenMock.sol

@@ -10,7 +10,7 @@ import "../token/ERC721/ERC721Token.sol";
  */
 contract ERC721TokenMock is ERC721Token {
   function ERC721TokenMock(string name, string symbol) public {
-    ERC721Token.initialize(msg.sender, name, symbol);
+    ERC721Token.initialize(name, symbol);
   }
 
   function mint(address _to, uint256 _tokenId) public {

contracts/token/ERC721/ERC721Token.sol

@@ -36,7 +36,7 @@ contract ERC721Token is Migratable, ERC721, ERC721BasicToken {
   /**
    * @dev Constructor function
    */
-  function initialize(address _sender, string _name, string _symbol) public isInitializer("ERC721Token", "1.9.0-beta") {
+  function initialize(string _name, string _symbol) public isInitializer("ERC721Token", "1.9.0-beta") {
     name_ = _name;
     symbol_ = _symbol;
   }

contracts/token/ERC721/MintableERC721Token.sol

@@ -9,7 +9,7 @@ import "../../ownership/Ownable.sol";
 contract MintableERC721Token is Migratable, Ownable, ERC721Token {
   function initialize(address _sender, string _name, string _symbol) isInitializer("MintableERC721Token", "1.9.0-beta") {
     Ownable.initialize(_sender);
-    ERC721Token.initialize(_sender, _name, _symbol);
+    ERC721Token.initialize(_name, _symbol);
   }
 
   function mint(address _to, uint256 _tokenId) onlyOwner public {