First usable version check-in

App works in the steps:
1. Init UI
2. Send Http POST Request asking for playlist
3. Download songs from playlist
4. Once a song has been downloaded, call Phonon to play it
5. Download next song

As mp3 title, artist name are utf-8 strings, using code:
QString mp3Title = QString::fromUtf8(str)
instead of
QString mp3Title = QString(str)