[webpack] break CSS and JS files while webpackin' (#3262)

* [webpack] break CSS and JS files while webpackin'

* cleaning up some templates

* Fix pylint issue

superset/assets/javascripts/SqlLab/index.jsx

@@ -10,7 +10,7 @@ import { initJQueryAjax } from '../modules/utils';
 import App from './components/App';
 import { appSetup } from '../common';
 
-import './main.css';
+import './main.less';
 import '../../stylesheets/reactable-pagination.css';
 import '../components/FilterableTable/FilterableTableStyles.css';
 

superset/assets/javascripts/SqlLab/main.less

@@ -161,7 +161,6 @@ div.Workspace {
     margin: 0px;
     border: none;
     font-size: 12px;
-    line-height: @line-height-base;
     background-color: transparent !important;
 }