fix: linting errors

contracts/bounties/BreakInvariantBounty.sol

@@ -4,6 +4,7 @@ pragma solidity ^0.4.24;
 import "../payment/PullPayment.sol";
 import "../ownership/Ownable.sol";
 
+
 /**
  * @title BreakInvariantBounty
  * @dev This bounty will pay out to a researcher if they break invariant logic of the contract.

contracts/token/ERC721/ERC721Burnable.sol

@@ -2,6 +2,7 @@ pragma solidity ^0.4.24;
 
 import "./ERC721.sol";
 
+
 contract ERC721Burnable is ERC721 {
   function burn(uint256 _tokenId)
     public

test/token/ERC721/ERC721.test.js

@@ -6,7 +6,6 @@ const {
 const {
   shouldSupportInterfaces,
 } = require('../../introspection/SupportsInterface.behavior');
-const _ = require('lodash');
 
 const BigNumber = web3.BigNumber;
 const ERC721 = artifacts.require('ERC721Mock.sol');

test/token/ERC721/ERC721Basic.test.js

@@ -1,7 +1,4 @@
 const { shouldBehaveLikeERC721Basic } = require('./ERC721Basic.behavior');
-const {
-  shouldBehaveLikeMintAndBurnERC721,
-} = require('./ERC721MintBurn.behavior');
 
 const BigNumber = web3.BigNumber;
 const ERC721Basic = artifacts.require('ERC721BasicMock.sol');

test/token/ERC721/ERC721Full.behavior.js

@@ -1,4 +1,5 @@
 const { assertRevert } = require('../../helpers/assertRevert');
+const _ = require('lodash');
 
 const firstTokenId = 100;
 const secondTokenId = 200;