Post login services region is not set

In a multi-region OpenStack deployment, horizon fails to remember the selected services region post-login. The cookie is properly set, but it's never used in the login_view to set the request.session['services_region'] value. The result is that the selected region is reset to whichever region is first in the list, even though the services_region cookie is different. Clicking on the available regions and switching to the correct one, will leave the services_region cookie intact, but properly set the value in the session.

This causes confusion for users that log in and find themselves on a different region than previously selected.