Gallery: splitout model code

apps/gallery/ajax/createAlbum.php

apps/gallery/ajax/getAlbums.php

apps/gallery/ajax/getCovers.php

apps/gallery/ajax/scanForAlbums.php

apps/gallery/ajax/thumbnail.php

apps/gallery/appinfo/app.php

apps/gallery/css/styles.css

apps/gallery/index.php

apps/gallery/lib/album.php

apps/gallery/lib/photo.php

apps/gallery/lib/scanner.php

apps/gallery/templates/view_album.php

lib/db.php