Add suport for clementine media player in now_playing segment

- Add support for clementine media player in now_playing segment.
- Add definitions for now_playing segment in default and solarized color schemes
- Refactor the code to reuse the common code for clementine and spotify players.

Shot:
![shot136](https://f.cloud.github.com/assets/641396/388446/60187a70-a6da-11e2-90a4-d296e7218a8b.png)