Added CD Ripping feature

After some work, I managed to do a prototyped version of a CD ripping feature. Code is still a little messy but I believe it's working. It's acessible via `Music -> Rip Audio Cd...` I have used mostly cdio and Clementine's own transcoder to convert wav files extracted from the cd to lighter formats. There are, however, a couple issues.

1. Clementine's native transcoder Seg Faulted upon converting wav to mp3. Since I could listen to the wav files generated and they converted to ogg with no problems, I guess this could be a gstreamer problem. If someone could provide wav files with which to test it, it would help to investigate.
1. TagLib and Ogg flac files don't go along very well, probably because the extension is the same, so TagLib fails with a read error
1. I'm new to Qt, so I couldn't style the UI very well, would appreciate a little help

Besides that, there're a couple of things which I see as the next steps:

1. Allow user to customize file name format, as K3B does: `%track_number% - %artist% - %name%`. Currently it's all saved as trackXX
1. Query CDDB to automatically fetch info about the album.

This was requested by #3490, I hope you guys appreciate it, will greatly appreciate feedback. Here's a screenshot of it:
![ripcd](https://f.cloud.github.com/assets/1175309/1898278/2a8ed658-7c16-11e3-9b2d-0fc2fec43480.png)