Multi-node setup: Fix keystone host

Fixes bug 1154587.

Use KEYSTONE_AUTH_HOST instead of SERVICE_HOST when setting nova auth
parameters. Also use KEYSTONE_AUTH_PROTOCOL instead of SERVICE_PROTOCOL.

Change-Id: I54f7f31f6b795833b38968f6beea68e429f01d55
Merge "Multi-node setup: Fix keystone host"