project.properties is a auto generated file, however, since it is checked in already, I decided to commit this change. The variables are chosen by Eclipse (Eclipse will not allow use methods or classes from sdk higher than this one). I can remove project.properties and add it to `.gitignore` but new users would have to run an adb command each time to regenerate this file. I believe this change can safely be ignored. More info: http://stackoverflow.com/a/8871842/2206385