build: Remove now-unused build rules
scripts/ostree-ls-big-files.js: New script to analyze repo files for size
Add postprocessing infrastructure

We remove the root password from all images.  The core/docker tree
also gets docs and some kernel drivers removed.
core: Add an environment variable to breakpoint post-yum
core: Fix rpmqa-sorted script to operate on $(pwd)

I'm not sure why it needs $(pwd) over ".", but oh well.
core/postprocess: If there's no /usr/bin/rpm, add rpm-manifest.txt

We really want people using these trees to know what went in it.  If
the tree doesn't actually have /usr/bin/rpm inside it, then do an
"rpm -qa | sort" and dump that into: /usr/share/rpm-manifest.txt

This will help our story with GPL compliance too.