Setting Default Album Art

If you have songs that don't have a specific piece of album art, you can define a default image url using the "default_album_art" key. Once again, this is handled on initialization.

	Amplitude.init({
		"songs": [
			{
				"name": "Song Name 1",
				"artist": "Artist Name",
				"album": "Album Name",
				"url": "/song/url.mp3",
				"cover_art_url": "/cover/art/url.jpg"
			},
			{
				"name": "Song Name 2",
				"artist": "Artist Name",
				"album": "Album Name",
				"url": "/song/url.mp3",
				"cover_art_url": "/cover/art/url.jpg"
			},
			{
				"name": "Song Name 3",
				"artist": "Artist Name",
				"album": "Album Name",
				"url": "/song/url.mp3",
				"cover_art_url": "/cover/art/url.jpg"
			}
		],
		"default_album_art": "/url/to/default.jpg"
	});