Bootstrap fixups to make sure we have createrepo at the right time
Make sure we have a valid package cache when using yum.
Refuse to install i686 packages on RHEL derivatives.
Fix mirror to get EPEL repo metadata from.
Refactor bootstrap to shrink our admin node container.

The opencrowbar/centos container was getting a little bloated.  This
pull request series refactors it to more strictly seperate package
installation from service management as well as rebasing on top of a
smaller centos base image.

The upshot is that the base admin container should be about half the
size it was.
Switch our default logging for chef bootstrapping runs to info.