os.rename failed when it move the file across devices/mount-points.
shutil.move allow to rename/move a file from one physical device to
another.

Conflicts:
	setup.py

(cherry picked from commit d01956ec)

This recipe was colliding with slapos.recipe.template
recipe.

Moreover, this is useless since slapos.recipe.template provide
the same functionality.

Conflicts:
	component/slapos/buildout.cfg
	slapos/recipe/pwgen.py

This was done in order to avoid copy-pasta, and to be
used in coming slapos.recipe.wrapper recipe.

This reverts commit b86284e6.