Packages: use a separate yum persistdir per cache
Packages: better stringification/representation of OnDemandDict
Packages: fixed read-only yum cache

Replaced incredibly stupid (mea culpa!) and race-condition-prone
system that toggled filesystem permissions (what was I thinking?!?)
with judicious application of the yum cacheonly option.
Yum: Removed unused import
bcfg2-info: fixed automatch
Packages: make opportunistic yum cache creation respect metadata=disabled