Add delete undo styles

This is much like Android's undo delete for notifications and mails and allows you to undo a deletion of a menu entry:

![screenshot from 2014-09-13 00 34 36](https://cloud.githubusercontent.com/assets/195053/4258155/0c3cf7f4-3acd-11e4-9e9c-51c63f73ccb5.png)


by using this html:

```html
<div class="app-navigation-entry-deleted">
    <div class="app-navigation-entry-deleted-description">Deleted feed Bild.de</div>
    <button class="icon-history" title="Undo"></button>
</div>
```

The history button undoes the deletion

@jancborchardt @jbtbnl @MorrisJobke @georgehrke @raghunayyar @LEDfan

Please also review the design and workflow.
Can you give this button a class? Since CSS works from right to left, this selector will look first at all buttons on the page and only then filter by ».app-navigation-entry-deleted«.

cc @owncloud/designers