fix(profiles): Remove mail provided hack.

Nothing in our system depends on mailbase/ssmtp any more so this
package.provided hack can go away.
fix(profiles): gut board package.provided

The intent of this file is to exclude dependencies from both the build
root in /build/amd64-usr and board images that would be pulled in but
aren't actually needed. Many of these are build utilities that need to
be provided by the SDK rather than the build root. The current state is
a bit confusing because we are actually including things like git but it
is also listed here and this somehow works due to version differences.

Additionally dev images will start including a working build environment
soon so may of these tools need to get built after all. To simplify
things everything has been removed except for the few packages that are
would get pulled into production images if it weren't for this file.

packages.provided actually shouldn't be used in this way, instead
controlling dependencies should be done via USE flags and possibly some
day the experimental HDEPEND ebuild variable.
feat(profiles): New generic/dev and generic/prod profiles.

The dev images are going to become complete build environments. Keeping
track of the differences between the two via profiles will be easier
than making the current prod and dev image scripts even more complex.
bump(sys-kernel/coreos-kernel): Update to 3.14.6
Merge pull request #672 from gregkh/kernel_update

bump(sys-kernel/coreos-kernel): Update to 3.14.6
bump(sys-apps/systemd): Mark 213 as stable.

Need to just start using this and see what happens. :)
Merge pull request #674 from marineam/systemd

bump(sys-apps/systemd): Mark 213 as stable.
Merge pull request #670 from marineam/provided

package.provided and new profiles
feat(profiles): Move portage permissions setting out of make.conf

Developer friendly permissions are fine as the default in CoreOS.
Merge pull request #675 from marineam/workdir

feat(profiles): Move portage permissions setting out of make.conf
fix(sys-apps/systemd): Fix build during stage1 bootstrap.

stage1 builds disable most use flags but systemd 213 fails to build if
kmod is disabled. Work around this by force-enabling the flag.
chore(metadata): Regenerate cache
Merge pull request #676 from marineam/fix-systemd

fix(sys-apps/systemd): Fix build during stage1 bootstrap.
Merge pull request #677 from marineam/metadata

chore(metadata): Regenerate cache
bump(sys-apps/baselayout): Updates for systemd
chore(systemd): remove gentoo-systemd-integration from systemd build
chore(sys-apps/systemd): Remove old version
chore(sys-apps/systemd): sync/cleanup systemd ebuilds.

Pull in some updates from upstream Gentoo.
As a follow up to the gentoo-systemd-integration removal prune the now
unused vanilla use flag and our custom openrc use flag along with it.
fix(sys-apps/systemd): Add tmpfiles rule for resolv.conf

This path has changed after v213 so it must be handled here instead of
baselayout now.
fix(coreos-base/oem-vagrant): disable VMware's hgfs

Suggested in https://github.com/coreos/coreos-vagrant/pull/127