Fix cinder Debian install procedure

This patch adds links to the "Respond to the prompts for" steps,
and removes the manual edition of cinder.conf for the
keystone_authtoken (as this is handled by Debconf).

Change-Id: Ia0db1dfd4ccd47845333acbc6000330c83c985fb
Backport: icehouse
Merge "Fix cinder Debian install procedure"