MusicApp - Fix music sources model (or popup) in multiprocess

In multiprocess the music sources model returns 1 entry even though it has more. When Spotify and/or web radio are uninstalled and installed again, then it updates fine.

Steps to reproduce:

1) Run Neptune and install Spotify

2) Close and run Neptune again

3) Go to music application and press sources tool button to see the music sources popup

4) Go to Online store, uninstall Spotify and install it again. Then repeat step 3. The list is now complete. 

Misbehaviour: 

Only AM/FM Radio is on the list the first the popup is opened. 

Expected behaviour:

AM/FM Radio and Spotify should appear both in the popup's list.