fix(profiles): Go back to the stable portage version

sys-apps/portage-2.1.12.2 is now stable which is new enough for us.
fix(coreos-overlay): Fix improper EAPI declarations

EAPI needs to be the first thing in an ebuild. This clears up useless
errors from tools scanning the tree like emirrordist.
fix(coreos-overlay): Add missing or fix incomplete Manifests

emirrordist will refuse to handle files that are not included in the
Manifest file. To keep things happy just sweep across the tree adding
them. (A lot of these packages could actually go away, but that is a
different project for another day).
fix(mobile-broadband): Remove workaround for bug that doesn't exist

Fix the last of the bogus errors in the coreos overlay, removing this
hack makes the SRC_URI lines valid again and all tools are happy now.
Merge pull request #32 from marineam/fix-digests

Fix digests