New features
1. Expandable Content: tap expand icon to show hidden text
2. Rich Table supports full screen mode
3. Add custom language for language field of the book information
4. Cover Editor: add background image
5. Import files from WebDAV server
6. Share text and image from Notes app into CBB
7. Update Dropbox SDK
8. Make use of beautiful and high-resolution Unsplash photos
9. Fix WebDAV problems
10. Bug fix
