add script to build android samples
Merge pull request #4027 from minggo/iss2905-adjust_folder

add script to build android samples
use build/android-build to build android samples, and update readme
Merge pull request #4029 from minggo/iss2905-adjust_folder

use build/android-build to build android samples, and update readme
Update CHANGELOG
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into developTouchEvent