Fix storyboard for ios 7 deployment
Fix storyboard for ios 7 deployment

NghiaTranUIT/FDWaveformView,ywzw2013/FDWaveformView,johnryan/FDWaveformView,fulldecent/FDWaveformView,ale0xB/FDWaveformView,solomon23/FDWaveformView,ywzw2013/FDWaveformView,dahiri-farid/FDWaveformView,andreamazz/FDWaveformView,NghiaTranUIT/FDWaveformView,solomon23/FDWaveformView,andreamazz/FDWaveformView,solomon23/FDWaveformView,andreamazz/FDWaveformView,NghiaTranUIT/FDWaveformView,johnryan/FDWaveformView,ale0xB/FDWaveformView,johnryan/FDWaveformView,solomon23/FDWaveformView,fulldecent/FDWaveformView,fulldecent/FDWaveformView,ale0xB/FDWaveformView,johnryan/FDWaveformView,ywzw2013/FDWaveformView,ale0xB/FDWaveformView,NghiaTranUIT/FDWaveformView,ywzw2013/FDWaveformView