Added [keystone_authtoken] section in /etc/nova/nova.conf

Closes-bug: #1250606

Change-Id: Id8e0f3521f7628cdd00e1d73d2d6a0db3ca3447b
backport: havana
Update nova flagmappings for libvirt group

Updated Nova flag mappings to reflect that libvirt specific flags are
moving to a "libvirt" group. This will take effect in the output when
the autoconfig tables are next generated.

Change-Id: Ia5e13ba6cc5678098018678edcc79ef91f31aca6
Closes-Bug: #1253822
Merge "Added [keystone_authtoken] section in /etc/nova/nova.conf"