Rails 4 ckeditor file upload

I'm using ckeditor in my rails projec and I have a problem with image uploading. I don't want everything that ckeditor have, that I wrote some simple config.js for it:

CKEDITOR.editorConfig = (config) ->
  config.language = 'pl'
  config.toolbar_Pure = [
    '/',
    { name: 'basicstyles', items: [ 'Bold','Italic','Underline','Strike','Subscript','Superscript','-','RemoveFormat' ] },
    { name: 'paragraph',   items: [ 'NumberedList','BulletedList','-','Outdent','Indent','-','Blockquote','-','JustifyLeft','JustifyCenter','JustifyRight','JustifyBlock','-','BidiLtr','BidiRtl' ] },
    { name: 'links',       items: [ 'Link','Unlink' ] },
    '/',
    { name: 'styles',      items: [ 'Styles','Format','Font','FontSize' ] },
    { name: 'colors',      items: [ 'TextColor','BGColor' ] },
    { name: 'insert',      items: [ 'Image','Table','HorizontalRule','PageBreak' ] },
  ]
  config.toolbar = 'Pure'
  true

and in my view:

= f.input :answer, label: false, :as => :ckeditor, :input_html => { :ckeditor => {:toolbar => 'Pure'} }

And with this config I don't have a button to select image from my computer:

But when I delete my config.js and in view set:

= f.input :answer, label: false, :as => :ckeditor, :input_html => { :ckeditor => {:toolbar => 'Full'} }

then I have the button to upload file from my computer and everything works fine. Now my goal is to edit my config.js to have this file upload working. Please help.

I change my config to:

CKEDITOR.editorConfig = function(config) {
  config.language = 'pl';
  config.filebrowserBrowseUrl = "/ckeditor/attachment_files";
  config.filebrowserFlashBrowseUrl = "/ckeditor/attachment_files";
  config.filebrowserFlashUploadUrl = "/ckeditor/attachment_files";
  config.filebrowserImageBrowseLinkUrl = "/ckeditor/pictures";
  config.filebrowserImageBrowseUrl = "/ckeditor/pictures";
  config.filebrowserImageUploadUrl = "/ckeditor/pictures";
  config.filebrowserUploadUrl = "/ckeditor/attachment_files";
  config.toolbar_Pure = [
    '/', {
      name: 'basicstyles',
      items: ['Bold', 'Italic', 'Underline', 'Strike', 'Subscript', 'Superscript', '-', 'RemoveFormat']
    }, {
      name: 'paragraph',
      items: ['NumberedList', 'BulletedList', '-', 'Outdent', 'Indent', '-', 'Blockquote', '-', 'JustifyLeft', 'JustifyCenter', 'JustifyRight', 'JustifyBlock', '-', 'BidiLtr', 'BidiRtl']
    }, {
      name: 'links',
      items: ['Link', 'Unlink']
    }, '/', {
      name: 'styles',
      items: ['Styles', 'Format', 'Font', 'FontSize']
    }, {
      name: 'colors',
      items: ['TextColor', 'BGColor']
    }, {
      name: 'insert',
      items: ['Image', 'Table', 'HorizontalRule', 'PageBreak']
    }
  ];
  config.toolbar = 'Pure';
  return true;
};

and works as expected