update artist and album search wigets immediately on arbum/track found

This allows the artist and albums in the search widget to update immediately when an artist/album is found instead of after the search has finished. The current implementation does a 

    m_albumsModel->clear();
    m_albumsModel->appendAlbums( sortedAlbums );

everytime an album/artist is added. This happens three times per search for me, but depends on how many resolvers you have activated.

I played with insertAlbums, but that looks exactly the same in the gui, so i figured adding the extra logic required for using insert instead of clear; append isnt worth it. What do you think?