Merge tag 'v2.1.1' of github.com:OpenZeppelin/openzeppelin-solidity

v2.1.1

contracts/mocks/ERC721Mock.sol

@@ -1,8 +1,7 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.0;
 
 import "../token/ERC721/ERC721.sol";
 
-
 /**
  * @title ERC721Mock
  * This mock just provides a public mint and burn functions for testing purposes
@@ -16,7 +15,11 @@ contract ERC721Mock is ERC721 {
         _mint(to, tokenId);
     }
 
+    function burn(address owner, uint256 tokenId) public {
+        _burn(owner, tokenId);
+    }
+
     function burn(uint256 tokenId) public {
-        _burn(ownerOf(tokenId), tokenId);
+        _burn(tokenId);
     }
 }