Absense of OS_AUTH_URL in config (env) leads to unusability

[gtema]

otc configure does not fill OS_AUTH_URL. Further usage (i.e. otc rds describe_db_instances) leads to "API not found", since API request with host IP (w/o hostname) is not reasonable.
It should be ensured, that OS_AUTH_URL is not empty and being populated during otc configure