Improve eslint rules (#3147)

* Add semi to ESLint rules

* Add padded-blocks to ESLint rules

* Add comma-dangle to ESLint rules

* add config/webpack and storyboard

* add streaming/

* yarn test:lint -- --fix

app/javascript/mastodon/components/column_back_button_slim.js

@@ -5,7 +5,7 @@ import PropTypes from 'prop-types';
 class ColumnBackButtonSlim extends React.PureComponent {
 
   static contextTypes = {
-    router: PropTypes.object
+    router: PropTypes.object,
   };
 
   handleClick = () => {
@@ -22,6 +22,7 @@ class ColumnBackButtonSlim extends React.PureComponent {
       </div>
     );
   }
+
 }
 
 export default ColumnBackButtonSlim;