Add ipv6 address for lo interface
Add ipv6 address for lo interface

setup-hosts play fails during first pass as lxcbr0 doesn't come up
because the ifup scripts depend on ipv6 address for lo interface.
Added kernel option to enable ipv6 on lo interface.

Change-Id: Ia0f067d11ce4d327f3bb83169c0f29af170b9229

openstack/openstack-ansible-openstack_hosts,openstack/openstack-ansible-openstack_hosts