v2.0 beta 4

This release focuses on improving the overall stability and usability.

• User guide for the most common tasks, watch for the "light bulb" icon on the action-bar.
• Add settings dialog with prefix customizing for launch shortcut, setup status and manual re-provisioning option to fix potential setup issues of Island.
• Improve the Greenify integration, with God mode fixed.
• App icon badge for launch shortcut is back.