Add icons for audio when sublinks

Before:
![screen shot 2014-10-21 at 17 41 10](https://cloud.githubusercontent.com/assets/1607666/4722681/3e2f9b76-5941-11e4-85ea-2aaeaaa0e3db.png)

After:
![screen shot 2014-10-21 at 17 39 37](https://cloud.githubusercontent.com/assets/1607666/4722690/4d1808bc-5941-11e4-9a92-a779187e0c9c.png)

Yeah not a bad shout. Might leave that for a later clean-up PR though, as that part of the code hasn't changed in this one.