Glance client does not handle authorization parameters correctly

[Simon Merrick]

glance image-list
'Namespace' object has no attribute 'os_username'

env | grep OS
OS_REGION_NAME=nz-hlz-1
OS_AUTH_TOKEN=[REDACTED]
OS_AUTH_URL=https://[REDACTED]:5000/v3
OS_PROJECT_ID=[REDACTED]
OS_AUTH_TYPE=token
OS_PROJECT_NAME=openstack-dev.[REDACTED]
OS_TOKEN=[REDACTED]
OS_IDENTITY_API_VERSION=3

[Simon Merrick (iokiwi)]

It appears to break on [shell.py#L343](https://github.com/openstack/python-glanceclient/blob/master/glanceclient/shell.py#L343) where there is an incorrect assumption that os_username is in the args Namespace.

This problem occurs for me with newer versions of glance client

 - 2.17.0
 - 3.0.0
 - 3.0.1

I don't have this problem with an older version of the glance client

 - 2.0.0

Looks like the keystone auth dependencies were switched out in 2.6.0 which may have impacted auth
https://github.com/openstack/python-glanceclient/commit/9ae5deb7fec11b4f19378cff044e25ad790b4688