Restructured and updated Nova networking sections

As part of the installation guide improvement project, I performed
the following operations on the Nova networking sections of the
installation guide:

1) Split configuration and initial network creation section to align
   with structure of Neutron chapter.
2) Aligned phrasing/wording and examples with Neutron chapter.
3) Removed defunct ch_neutron.xml from repository.
4) Modified links affected by these changes.
5) Updated glossary as necessary.

Change-Id: I690a7c2565826f4370940a716a6200e974211d8f
Partial-Bug: #1291071
Implements: blueprint networking-install-guide-improvements
Merge "Restructured and updated Nova networking sections"