0.1.15 release

Fixed issues and improve a few features, and implement End to End Encryption.

Improvements:

• End to End Encryption implemented (beta)
• Speed up boot file checking.
• Show status on Dropping history and set E2E

Fixes:

• Fix replication issue that reflects own changes again.
• Fix replication issue about unexpected error message is shown.
• Fix replication issue on mobile (Excessive resolution of modified time)
• Fix issue about the error on initializing.

related #10