fix(coreos-base/coreos-installer): Set correct source path in repo.

Use local repo checkout instead of falling back to git-2.eclass,
otherwise local development doesn't work.
bump(coreos-base/coreos-installer): Use fixed version of setgoodroot.

Now maybe upgrades work for more than one boot!
Merge pull request #193 from marineam/setgoodroot

Fix setgoodroot