Install Guide: Fix OS_AUTH_URL

Fix two places that used 127.0.0.1 as hostname instead of
controller as in the rest of the guide.

Change-Id: Ibc2bbb580c7b5c00bbed4dfa8071ca4596222d6b
backport: havana
(cherry picked from commit 5afb31f0c49f62c692cd1282cc48d97412fd9b50)