filters of workspace content now keep empty folder

src/component/Workspace/Folder.jsx

     } = this.props
 
     return (
-      <div className={classnames('folder', {'active': this.state.open, 'item-last': isLast})}>
+      <div className={classnames('folder', {'active': this.state.open && folderData.content.length > 0, 'item-last': isLast})}>
         <div className='folder__header align-items-center' onClick={this.handleClickToggleFolder}>
 
           <div className='folder__header__triangleborder'>

src/container/Tracim.jsx

   getUserIsConnected
 } from '../action-creator.async.js'
 import {
-  removeFlashMessage, setUserConnected
+  removeFlashMessage,
+  setUserConnected
 } from '../action-creator.sync.js'
 
 class Tracim extends React.Component {

src/container/WorkspaceContent.jsx

     ? contentList
     : contentList.filter(c => c.type === 'folder' || filter.includes(c.type)) // keep unfiltered files and folders
       .map(c => c.type !== 'folder' ? c : {...c, content: this.filterWorkspaceContent(c.content, filter)}) // recursively filter folder content
-      .filter(c => c.type !== 'folder' || c.content.length > 0) // remove empty folder
+      // .filter(c => c.type !== 'folder' || c.content.length > 0) // remove empty folder => 2018/05/21 - since we load only one lvl of content, don't remove empty folders
 
   render () {
     const { workspace, app } = this.props