remove react-web3 library

src/index.js

 import React from 'react';
 import ReactDOM from 'react-dom';
-import { Web3Provider } from 'react-web3';
 import './index.css';
 import App from './App';
-
-{/*
-ReactDOM.render(
-  <Web3Provider>
-   <App />
-  </Web3Provider>, document.getElementById('root')
-);
-*/}
+import registerServiceWorker from './registerServiceWorker';
 
 ReactDOM.render(
    <App />, document.getElementById('root')
 );
+registerServiceWorker();