Music: keyword search and SoundCloud are back

Continuation of music player things, with a potential resolution wooooo.

Hey there! So, I finally got what I was working on since some days for audio, it is working and it's live on Martine. Just let me explain you some important things:
1. On the last announce, I said that searching a track using a keyword was disabled, it has been enabled back. You can now use the music player normally without needing provide a link for every music you want to play.
2. Soundcloud support is back. It was disabled since a while now, you can now enjoy back your Soundcloud playlists or other!
3. Also a few fixes globally in music player that some of you noticed. Thanks for your reports.

Note: About first point, it is back, but for now please consider this as a live test, I really hope it will works as it should, so without bans all the f*cking time.