Merge lp:~rockstar/ubuntuone-ios-music/fix-crasher into lp:ubuntuone-ios-music

[Paul Hummer]

Fix a crash in NowPlayingInfoCenter

Crashlytics reported this crash not long after I put out (and then removed) a TestFlight build.

[Brian Curtin (brian.curtin)]

review: Approve

=== modified file 'Music/Utilities/UOPlayer.m'
--- Music/Utilities/UOPlayer.m	2013-02-13 20:32:27 +0000
+++ Music/Utilities/UOPlayer.m	2013-02-14 02:20:28 +0000
@@ -280,11 +280,12 @@
 
 - (void)songChanged {
     Song *song = [[self currentPlaylist] objectAtIndex:self.currentIndex];
+    UIImage *artwork = song.art != nil ? song.art : [UIImage imageNamed:@"default-album-art-640.png"];
     NSDictionary *songInfo = @{MPMediaItemPropertyAlbumTitle: song.album.title,
                                MPMediaItemPropertyAlbumTrackCount: [NSNumber numberWithInt:[song.album.songs count]],
                                MPMediaItemPropertyAlbumTrackNumber: [NSNumber numberWithInt:song.track],
                                MPMediaItemPropertyAlbumArtist: song.albumArtist ? song.albumArtist.name : song.artist.name,
-                               MPMediaItemPropertyArtwork: [[MPMediaItemArtwork alloc] initWithImage:song.art],
+                               MPMediaItemPropertyArtwork: [[MPMediaItemArtwork alloc] initWithImage:artwork],
                                MPMediaItemPropertyPlaybackDuration: [NSNumber numberWithInt:song.duration],
                                MPMediaItemPropertyTitle: song.title,