Create a version def.

Change-Id: Idde38773c60a4c051f30f7256873e03b384a3e18
Refactor code for android build.

Change-Id: I3e721fdebf582eb7f26e898623a42442f8b98cbb
Improve utilities for android platform

- Add utility functions for typing.
- Add utility for screenshot.

Change-Id: I31cf692e69dbf9e09ddc28e72500eb45a7773e37
Add gitignore

Change-Id: I037d2fdbb9c844584b4e4898218f8028967e7280