Dashboard loading (#142)

* Fixed: Loading indicator never appears
Added: Loading indicator to dashboard when loading first results

* Less assumptions

* Fixes: Image uploads not working

* Fixes #136 - Keyboard shortcuts should work when editor is not focused

* Allow images to be dragged anywhere on document editor

* Fixes #137 - vertical alignment

* Restore shortcuts with editor focus

* Restore 'e' to edit current document
Fixed up ? to open keyboard shortcuts

* wip

* LoadinglistPlaceholder

* WIP

* Refactor

* DRY logic

frontend/components/LoadingPlaceholder/ListPlaceholder.js

@@ -0,0 +1,33 @@
+// @flow
+import React from 'react';
+import ReactCSSTransitionGroup from 'react-addons-css-transition-group';
+import styled from 'styled-components';
+import Mask from './components/Mask';
+import Flex from 'components/Flex';
+
+export default (props: Object) => {
+  return (
+    <ReactCSSTransitionGroup
+      transitionName="fadeIn"
+      transitionAppearTimeout={0}
+      transitionEnterTimeout={0}
+      transitionLeaveTimeout={0}
+      transitionAppear
+      transitionEnter
+      transitionLeave
+    >
+      <Item column auto>
+        <Mask header />
+        <Mask />
+      </Item>
+      <Item column auto>
+        <Mask header />
+        <Mask />
+      </Item>
+    </ReactCSSTransitionGroup>
+  );
+};
+
+const Item = styled(Flex)`
+  padding: 18px 0;
+`;