Adding utils file to retrieve env vars for Rackspace auth
Rename utils.go to auth_env.go
Update Keystone v3 usage
Moving util function into root package to avoid import cycle
Update Keystone v3 to use new util location
It's useful to have the right package name
Updating all refs to previous AuthOpions func
Merge pull request #250 from jamiehannaford/auth-utils

Auth utils