Moved firewall section and restructured Compute section

Moved firewall section from CRG Compute to CAG Compute.
Renamed log-file chapter to match other 'file' chapter.
Moved Compute sections into files to trim down the massive
Compute chapter file. Edited touched files.
In section_cli_nova_volumes.xml, added example and one new option.
In section_compute-rootwrap.xml, added note with
NFS share info.
In section_system-admin.xml:
* Added new services.
* Replaced deprecated nova-manage commands with nova.

Change-Id: Ie300a9ce25d305b80bb0b21d3cfc318909f3a123
Merge "Moved firewall section and restructured Compute section"