Moves note about Ubuntu 12.04 LTS with GRE

Change-Id: Iab4fd385ee19aef96be51580f4efa8df44259976
Closes-bug: 1251714
Edit Manage Images section in User Guide

Adds options to update disk_bus and cdrom_bus metadata properties based on the configured hypervisor type

Change-Id: I11ca56450dfbf4e51a2908206f7d6c664c83fd9b
author: nermina miller
backport: havana
Closes-Bug: #1106421
Merge "Moves note about Ubuntu 12.04 LTS with GRE"
Merge "Edit Manage Images section in User Guide"