incomplete
possibly cleaner
split out retry and auth in separate func - not working
Merge branch 'master' into cache_our_token
working with tests
Logging when getting token
failure cases return UpstreamError
retry_on_unauth tests
docs corrected
better log - thanks @cyli
sample auth raises different exception - thanks @cyli

Also, added test to ensure that auth errors are propogated
correct assertion
block_device_mapping must be provided if image ref is empty
Add block_device_mapping to all the autoscale fixtures and clients
Fix test_create_scaling_group to pass block_device_mapping to the positive tests
Add negative tests for when an empty image ID is passed without block device mapping
Change system test for bfv to include block_device_mapping
Add block_device_mapping to test_update_launch_config
Merge pull request #716 from rackerlabs/cache_our_token

AS-290: ImpersonatingAuthenticator caches token
Change delete_on_termination to True so the volume gets cleaned up when the test server is deleted - thanks @manishtomar