Change I60162b54bc06e158534d29311d4474b34750c64d
removed the `/v3` prefix from the WEBSSO_KEYSTONE_URL
variable. However, keystone endpoints do in fact
have the `/v3` prefix, and Horizon expects the
WEBSSO_KEYSTONE_URL variable to already contain
the prefix.
This patch adds the prefix again so that SSO
works with Horizon again.
Closes-Bug: #2028921
Change-Id: I5799f7a6fa4f52c2904b14fc02ed18443f4194bd
Signed-off-by: Juan Pablo Suazo <jsuazo@whitestack.com>