fix(extend-expect): remove expect import

Closes #34

Author: Kent C. Dodds

src/extend-expect.js

@@ -1,7 +1,4 @@
-import expect from 'expect' //eslint-disable-line import/no-extraneous-dependencies
 import extensions from './jest-extensions'
 
 const {toBeInTheDOM, toHaveTextContent} = extensions
 expect.extend({toBeInTheDOM, toHaveTextContent})
-
-export default expect