Install Guide: Correct Neutron Section Tree

This commit moves around a couple of pieces of the install guide
neutron documentation. The actuall root install section now no
longer refers to the network node; that now has its own subsection.
Additionally, the instructions for initializing the database are
now in the root section.

This is the final commit in the series.

Change-Id: I94cd2b1cac9fae9936110ecaedf13c6eb895a2a8
backport: havana
(cherry picked from commit c17bd5f6e5301cfb2651b97d034536611eef883f)
Install Guide: Cleanup for ch_basics

Cleanup usage of os to use only the right tags (for example only "sles"
for a SLES section)
Fix some screen sections to display better
Install openstack-utils on openSUSE/SLES
Fix typos

Change-Id: I031ae4102eee12a69eb1a4271f563866123ba980
(cherry picked from commit 8c29b9c76c77b755cf6425ebb1d18c666ef30563)
Merge "Install Guide: Cleanup for ch_basics" into stable/havana