sound_cloud.js: Get the `<script>` tag in the callback.

We should get the `<script>` tag in the callback function (the `$('[src*="/js/spice/sound_cloud/"]')`) since the call to `/js/spice/sound_cloud/` might not exist yet when `sound_cloud.js` loads.

![screen shot 2014-07-09 at 1 59 00 pm](https://cloud.githubusercontent.com/assets/81969/3528774/c377ca02-0792-11e4-91c2-9daefee2273b.png)
![screen shot 2014-07-09 at 1 36 55 pm](https://cloud.githubusercontent.com/assets/81969/3528773/c3777a34-0792-11e4-8ae6-f1b47b4449bf.png)