Fix the bug when audio file contains artwork.
Fix the bug when audio file contains artwork.

Fix Issue #6.

QiuZhiFei/DOUAudioStreamer,QiuZhiFei/DOUAudioStreamer,cute/DOUAudioStreamer,zhantss/DOUAudioStreamer,zhantss/DOUAudioStreamer,hjw6160602/DOUAudioStreamer,jonesgithub/DOUAudioStreamer,Learn-IOS/DOUAudioStreamer,vinceee/DOUAudioStreamer,vinceee/DOUAudioStreamer,NghiaTranUIT/DOUAudioStreamer,talkmate/DOUAudioStreamer,cute/DOUAudioStreamer,zhouwude/DOUAudioStreamer,douban/DOUAudioStreamer,royalwang/DOUAudioStreamer,sunfei/DOUAudioStreamer,xuanyi0627/DOUAudioStreamer,talkmate/DOUAudioStreamer,hjw6160602/DOUAudioStreamer,eyu1988/DOUAudioStreamer,douban/DOUAudioStreamer,royalwang/DOUAudioStreamer,xuanyi0627/DOUAudioStreamer,royalwang/DOUAudioStreamer,eyu1988/DOUAudioStreamer,Learn-IOS/DOUAudioStreamer,hjw6160602/DOUAudioStreamer,ycaihua/DOUAudioStreamer,jonesgithub/DOUAudioStreamer,sunfei/DOUAudioStreamer,ycaihua/DOUAudioStreamer,zhouwude/DOUAudioStreamer,sunfei/DOUAudioStreamer,NghiaTranUIT/DOUAudioStreamer,NghiaTranUIT/DOUAudioStreamer,xuanyi0627/DOUAudioStreamer