Allow user to choose command per station. Small fixes.

This PR does a few things:

- Brings default station list in sync with master.
- Removes a line that overwrites the vim statusline.
- Adds an optional argument to user-configured stations. This allows the user to specify a station in `g:unite_source_radio_stations` as `[name, url, player-command]`. Please see [the commit comment](https://github.com/appleYaks/unite-radio.vim/commit/2a24c7ab0de5845f5fc9736c80a05ce69a0cdbb9#comments) for more info.