Enhances and updates bare metal information

Adds back in the section about booting to a specific node/host

- points to correct wiki page
- gives more use cases and context

Change-Id: I71a85860108a4e7220a69c3e54b467dfc575f8c3
Closes-bug: 1226511
Closes-bug: 1188474
Check also for non-xml include files

Check for any type of include file, not just xml files.

Change-Id: I1290ee317b7b7787e16f204c9780f0811773ff8f
Move nova.conf/neutron.conf database configuration variables to [database] section

Commit https://review.openstack.org/34671 introduced for nova.conf:
"The database configuration variables are now in a new section
 [database]."

This change is also needed for the neutron files.

Change-Id: I3dcc46c163560e6ca277d421acf87a75683fa83d
Partial-Bug: #1205060
Document Nicira NVP L3 Advanced Features Extension

Fixes bug: 1226395

Change-Id: I22c45bdeb9da18026ad6521f0dd2c475bc822592
Remove duplicate file common/section_identity_troubleshooting.xml

This file is not used anywhere and its content is part of the
file common/section_identity-troubleshooting.xml.

Change-Id: I8b1926b0c6c9ab2c7f90a1ea426f947051793a32
Merge "Enhances and updates bare metal information"
Merge "Move nova.conf/neutron.conf database configuration variables to [database] section"
Merge "Check also for non-xml include files"
Merge "Document Nicira NVP L3 Advanced Features Extension"
Merge "Remove duplicate file common/section_identity_troubleshooting.xml"