* Fixed #18: Builds fail on Ubuntu 13.04 with zlib.h missing.
* Fixed missing rebuild of build.py when the previous build failed.
Merge branch 'master' of https://github.com/kivy/buildozer

Conflicts:
	buildozer/targets/android.py
Merge pull request #20 from roskakori/master

Fixed #18: Builds fail on Ubuntu 13.04 with zlib.h missing.