added sound and updated readme
Merge branch 'master' of https://github.com/stanzheng/HackU2
Merge branch 'master' of https://github.com/stanzheng/HackU2
Merge branch 'master' of https://github.com/guywithnose/HackU2
Merge branch 'master' of https://github.com/stanzheng/HackU2
updated readme and added playstore link