Extend document-tooltip with download copy link.

:construction: 
The Document tooltip should be extend with the download copy link (see image):
![ohne titel](https://cloud.githubusercontent.com/assets/485755/3222900/7ae01a66-f01c-11e3-9958-28fbfc9e709d.png)

Example:
![bildschirmfoto 2014-06-09 um 23 19 49](https://cloud.githubusercontent.com/assets/485755/3222856/0268e220-f01c-11e3-9835-662251ea7981.png)

Todos:
- [x] Adjust tooltip helper
- [x] CSS Adjustments (width etc.)
- [x] Tests
- [ ] Maybe adjustments in the download copy confirmation.

You need to update the `id` of the JS resource after dropping the explicit single-resource registration. -> `++resource++opengever.base/prepoverlay.js`