adding foo.txt to sample app 1
Edit foo.txt from app #2
Remove common code that is being moved to library
Adding common code from library to app #1

git-subtree-dir: common
git-subtree-mainline: e19f70fd705a50ab07ed30452ce89e94ef4a2727
git-subtree-split: 2d3116b4ad773f40a6f0b3d775a4ae3199350bb7