重写SectionIndexer
终于没有的字母不会再出现了

Signed-off-by: Harry Chen <373685963@qq.com>
Merge branch 'master' of https://github.com/PaperAirplane-Dev-Team/Music-Share-Android

# By Xavier Yao
# Via Xavier Yao
* 'master' of https://github.com/PaperAirplane-Dev-Team/Music-Share-Android:


Conflicts:
	src/com/paperairplane/music/share/IntentResolver.java
	src/com/paperairplane/music/share/Main.java
	src/com/paperairplane/music/share/MusicListAdapter.java

Signed-off-by: Harry Chen <373685963@qq.com>