Add depsolving utility

Add a dependency ordering utility.
It is not wired into the Bash processing yet.
Merge pull request #134 from encukou/depsolving

WIP: Add depsolving utility
build.py: Fail when ant process fails

- Use check_call to raise CalledProcessError if somethig goes wrong
- Use a for loop instead of map()
use depsort.py tool to order the module compilation.

It's work magically, that's soooooo great!
Merge pull request #135 from encukou/check_call

build.py: Fail when ant process fails
remove baaad exit
Merge branch 'master' of ssh://github.com/kivy/python-for-android