Porting Flask to Django Framework

[9gix]

• [x] RESTful Resource API (Song, Skill, WarmUp, SongSkill, WarmUpSong)
• [x] New! Admin Interface
• [x] New! Browsable API
• [ ] Test Case
• [ ] Deployment

Don't merge this branch yet, until everyone agree to do so. Because it completely replace the whole logic that we have ever done in Flask Framework.