[rackspace] adding metadata methods on container model
[rackspace] adding metadata methods on container model

mcanthony/pkgcloud,mdsummers/pkgcloud,apla/pkgcloud,andrewsomething/pkgcloud,pkgcloud/pkgcloud,bunglestink/pkgcloud,Phanatic/pkgcloud,Phanatic/pkgcloud,hacor/pkgcloud,dionjwa/pkgcloud,DonSchenck/pkgcloud,Hopebaytech/pkgcloud,songanbui/pkgcloud,temka1234/pkgcloud