[FLOC-1030] Generate tutorial box with omnibus packages.

https://clusterhq.atlassian.net/browse/FLOC-1030

This needs to be merged along with its sibling issues.

Also, buildbot needs to be adjusted so that the omnibus rather than native package build triggers the tutorial builder.
I always assumed that the `$releasever` and `$arch` in the repo path were significant and that `yum` required that pattern. I guess not.