Removed gradient & text from large album cover (Issue #853)

Hello, this is my attempt to address issue #853 and make the large album art widget better. This simply removes the black gradient and text over the large album cover to give a cleaner interface and show off the album art better. If the user wants the song information next to the album art, they can still switch to the small album art. Thank you!
![tv6yjgl](https://cloud.githubusercontent.com/assets/4236749/2905509/d3985ba4-d605-11e3-9abd-eb83252bee30.png)