Proposition to add a network descriptor in the pdf file

Proposition to add a network descriptor in the pdf file

linked with patch 36297

Add a network descriptor in the file.
The network descriptor contains what is in the wiki
Each network is linked to an interface number, who refer to an interface
  on each server.
Each nodes, list only mac addresses that are used, and plugged, in order
Each nodes can specify ip addresses for each interfaces, it is optionnal
  depending on installer choice
This solution split network definition and node definition that contains
  only physical informations

Updated this patchset to fix typos
we could rename the net_config names to be less openstack specific
But I don't think it hurts and deploying openstack is a major usecase.

Change-Id: I27f4a56db0e50436f5c59e1645b6d2c4c9b8ae5c
Signed-off-by: Blaisonneau David <david.blaisonneau@orange.com>
Signed-off-by: agardner <agardner@linuxfoundation.org>
Signed-off-by: Julien <zhang.jun3g@zte.com.cn>
Signed-off-by: Blaisonneau David <david.blaisonneau@orange.com>