The `openstack_auth login` view uses `request.build_absolute_uri` function
to build an origin uri when websso is enabled and
the WEBSSO_DEFAULT_REDIRECT_PROTOCOL is set.
This function doesn't insert the `WEBROOT` variable into uri what causes an
error:
http://domain.name/auth/websso/ is not a trusted dashboard host
Using the `build_absolute_uri` from `utils` module fixes this problem. It
generates the right uri:
http://domain.name/dashboard/auth/websso/
Change-Id: I94100f66a9f07eb8da75d344cbd120838fe25d1e
2842d7df37