• Added jwt.OnDemandCredentials. (#142)
• Added new public property id_token to oauth2.credentials.Credentials. (#150)
• Added the ability to set the address used to communicate with the Compute Engine metadata server via the GCE_METADATA_ROOT and GCE_METADATA_IP environment variables. (#148)
• Changed the way cloud project IDs are ascertained from the Google Cloud SDK. (#147)
• Modified expiration logic to add a 5 minute clock skew accommodation. (#145)