Major: 0.0.112

New Features:
1. Add CoverImage to Database.
2. KNMusicModel will control how to give out the data.
3. Now use int instead of QModelIndex to highlight the data.

Update:
1. Change the requireOpenUrl connect in KNMusicPlugin into Qt 5 style.

Bug Fixed:
1. Fixed a memory leak bug in KNMusicPlugin when exit.
Major: 0.0.113

New Features:
1. Now use a stupid way to rebuild category list.