Now able to play a single file, in a format supported by your browser.
* Playlists not yet supported.
* Volume is a simple on/off switch.
* Repeat / Random not yet supported.
* Build everything in `public/` folder, to serve only this and avoid
issues with `publicPath` in webpack.
* Moved some icons to FontAwesome and use spinning wheels from
FontAwesome to indicate loading.
* (Very) beginning of a webplayer.