heat-keystone-setup : fix error on folsom first-install

heat-keystone-setup : fix error on folsom first-install

When running heat-keystone-setup for the first time after (re)installing
openstack folsom, it fails, because the user-role-list is running *as* the
heat user, not reading the roles assigned to the heat user, which fails
because on a new install the heat user does not have the admin role.
Using the credentials from the environment means we run the command as
admin, but --user_id selects the roles for the heat user.

Change-Id: Ib2733e63f664d75be1e2e3bd43038bbd1dbebde8
Signed-off-by: Steven Hardy <shardy@redhat.com>