Extrapolate OS_ env vars for other auth options.
Extrapolate OS_ env vars for other auth options.

larsbutler/gophercloud,dudymas/gophercloud,sti-jans/gophercloud,feiskyer/gophercloud,DSpeichert/gophercloud,carolynvs/gophercloud,jarosser06/gophercloud,rackspace/gophercloud,jamiehannaford/gophercloud,clintonskitson/gophercloud,trumant/gophercloud,rgbkrk/gophercloud,trumant/gophercloud,dudymas/gophercloud,clintonskitson/gophercloud,carolynvs/gophercloud,DSpeichert/gophercloud,larsbutler/gophercloud,sti-jans/gophercloud,pratikmallya/gophercloud,pratikmallya/gophercloud,timbyr/gophercloud,jamiehannaford/gophercloud,rackspace/gophercloud,feiskyer/gophercloud,timbyr/gophercloud,rgbkrk/gophercloud,jarosser06/gophercloud