Move standalone ERC20 and ERC721 to token dir (#38)

contracts/examples/StandaloneERC20.sol → contracts/token/ERC20/StandaloneERC20.sol

 pragma solidity ^0.4.24;
 
 import "zos-lib/contracts/Initializable.sol";
-import "../token/ERC20/ERC20Detailed.sol";
-import "../token/ERC20/ERC20Mintable.sol";
-import "../token/ERC20/ERC20Pausable.sol";
+import "./ERC20Detailed.sol";
+import "./ERC20Mintable.sol";
+import "./ERC20Pausable.sol";
 
 
 /**

contracts/examples/StandaloneERC721.sol → contracts/token/ERC721/StandaloneERC721.sol

 pragma solidity ^0.4.24;
 
 import "zos-lib/contracts/Initializable.sol";
-import "../token/ERC721/ERC721.sol";
-import "../token/ERC721/ERC721Enumerable.sol";
-import "../token/ERC721/ERC721Metadata.sol";
-import "../token/ERC721/ERC721MetadataMintable.sol";
-import "../token/ERC721/ERC721Pausable.sol";
+import "./ERC721.sol";
+import "./ERC721Enumerable.sol";
+import "./ERC721Metadata.sol";
+import "./ERC721MetadataMintable.sol";
+import "./ERC721Pausable.sol";
 
 
 /**

test/examples/StandaloneERC20.test.js → test/token/ERC20/StandaloneERC20.test.js

 const encodeCall = require('zos-lib/lib/helpers/encodeCall').default;
-const { shouldBehaveLikeERC20Mintable } = require('../token/ERC20/behaviors/ERC20Mintable.behavior');
-const { assertRevert } = require('../helpers/assertRevert');
+const { shouldBehaveLikeERC20Mintable } = require('./behaviors/ERC20Mintable.behavior');
+const { assertRevert } = require('../../helpers/assertRevert');
 
 const BigNumber = web3.BigNumber;