Install Guide: Setup first config files, then run openstack-db

Change-Id: I778c246bcb3fbb89bc31f4b52861813619baf759
Backport: stable/havana
Closes-Bug: #1242602
Install Guide: Consistent root command usage

The guide does not use sudo as explained in ch_basics, so remove
its usage and change prompts to #.

Change-Id: I4e25e700bd070a5aca701eb2413b86e780f47192
Backport: stable/havana
Merge "Install Guide: Consistent root command usage"
Merge "Install Guide: Setup first config files, then run openstack-db"