Update GeographicalCloudIdentityProvider to extend ProviderBase
Remove CloudInstance enumeration; CloudIdentityProvider always uses a single specified endpoint
Removed CloudIdentityProvider; renamed GeographicalCloudIdentityProvider to replace it
Updated documentation for impersonation Authenticate
Rename Authenticate to Impersonate to distinguish it from other authentication requests
Update code to not ignore the Domain property of RackspaceCloudIdentity
Merge pull request #190 from sharwell/global-auth

Global auth changes