Add domain attributes to accessinfo

user_domain_id and project_domain_id are already available, so simply
add an equivalent user_domain_name and project_domain_name if available.

The use of 'default' for v2 tokens is inspired from the default behaviour of
similar functions and what is used in auth_token middleware.

Change-Id: Ia9b345529072ab893d04c7a38fb7ba3acdc28227
Merge "Add domain attributes to accessinfo"