[#1405] Fix rendering position of link to this box

Fixes #1405 

Needed to require `jquery.ui.position` now that we've moved to the jQuery UI gem.

I've also modified the positioning slightly:

**Previous:**

![screen shot 2014-03-28 at 16 43 15](https://cloud.githubusercontent.com/assets/282788/2552433/5add86c0-b699-11e3-8543-2075eb924219.png)

**New:**

![screen shot 2014-03-28 at 16 43 56](https://cloud.githubusercontent.com/assets/282788/2552434/6331fd6a-b699-11e3-92ba-6ab38027b157.png)

![screen shot 2014-03-28 at 16 44 21](https://cloud.githubusercontent.com/assets/282788/2552437/68c3ced4-b699-11e3-96c3-a37cd32d0b88.png)

![screen shot 2014-03-28 at 16 44 38](https://cloud.githubusercontent.com/assets/282788/2552439/708b4bce-b699-11e3-817b-9550988e22c7.png)