Severity: wishlist

The first patch (for elpa.git) below makes `use-package' and `bind-key'
into :core packages.  This is the first step towards retiring the old
use-package GitHub repository.[1]

The second patch makes use-package-ensure-system package into its own
separate :core package, just as it has been on MELPA.[2]  This would
facilitate users' transition, and also by installing it they will get
the necessary `system-packages' package installed as a dependency.

Stefan, does this look okay and make sense to you?  Is pushing this all
that is needed, or do we need some manual intervention in addition?