Don't log when we load a repository

That happens a lot, and it's not really interesting.  This patch also
adds back in the "Nothing to do" message for most commands, if they
don't result in any meaningful work happening.
buzzy uninstall

The new `buzzy uninstall` command removes a package from the system.  We
don't check the version that was installed; if some other version that
the “current” version is installed, we'll go ahead and remove that.  We
also don't check any forward dependencies; most package managers will
refuse to uninstall a package if there's some other package installed
that depends on it.
Merge branch 'feature/uninstall' into develop

* feature/uninstall:
  buzzy uninstall
  Don't log when we load a repository