Fix linter errors

.prettierignore

@@ -2,3 +2,4 @@ lib
 generated
 .nyc_output
 /packages/contracts/build/contracts
+package.json

packages/0x.js/test/ether_token_wrapper_test.ts

@@ -17,7 +17,6 @@ import {
     ZeroEx,
     ZeroExError,
 } from '../src';
-import { artifacts } from '../src/artifacts';
 import { DoneCallback } from '../src/types';
 
 import { chaiSetup } from './utils/chai_setup';