plugin: Write out state file via create-new-then-rename
plugin: Write out state file via create-new-then-rename

This makes updates atomic, so it's useful generally.  However
I'm making this change specifically to support rpm-ostree.

For more information, see:
https://bugzilla.redhat.com/show_bug.cgi?id=1352152

krig/vagrant,benizi/vagrant,sni/vagrant,mwrock/vagrant,bryson/vagrant,sni/vagrant,bshurts/vagrant,tomfanning/vagrant,marxarelli/vagrant,taliesins/vagrant,justincampbell/vagrant,crashlytics/vagrant,chrisroberts/vagrant,benizi/vagrant,mitchellh/vagrant,bshurts/vagrant,kamazee/vagrant,gitebra/vagrant,signed8bit/vagrant,chrisroberts/vagrant,chrisroberts/vagrant,tomfanning/vagrant,taliesins/vagrant,jtopper/vagrant,kamazee/vagrant,benh57/vagrant,crashlytics/vagrant,bdwyertech/vagrant,krig/vagrant,carlosefr/vagrant,chrisroberts/vagrant,krig/vagrant,justincampbell/vagrant,crashlytics/vagrant,signed8bit/vagrant,benh57/vagrant,mitchellh/vagrant,mwrock/vagrant,bdwyertech/vagrant,marxarelli/vagrant,mwrock/vagrant,jtopper/vagrant,bryson/vagrant,bshurts/vagrant,mitchellh/vagrant,lukebakken/vagrant,gitebra/vagrant,lonniev/vagrant,marxarelli/vagrant,marxarelli/vagrant,lukebakken/vagrant,gitebra/vagrant,kamazee/vagrant,carlosefr/vagrant,carlosefr/vagrant,benizi/vagrant,benizi/vagrant,jtopper/vagrant,benh57/vagrant,lonniev/vagrant,PatrickLang/vagrant,lonniev/vagrant,lukebakken/vagrant,bdwyertech/vagrant,PatrickLang/vagrant,gitebra/vagrant,PatrickLang/vagrant,justincampbell/vagrant,kamazee/vagrant,bryson/vagrant,benh57/vagrant,mitchellh/vagrant,signed8bit/vagrant,mwrock/vagrant,sni/vagrant,PatrickLang/vagrant,taliesins/vagrant,taliesins/vagrant,tomfanning/vagrant,bryson/vagrant,sni/vagrant,bshurts/vagrant,signed8bit/vagrant,krig/vagrant,justincampbell/vagrant,lonniev/vagrant,lukebakken/vagrant,bdwyertech/vagrant,carlosefr/vagrant,crashlytics/vagrant,jtopper/vagrant,tomfanning/vagrant