Restart libvirt-bin when reconfiguring.

Otherwise configuration changes don't take effect.

Change-Id: Ia233997127d3295adbb5d7c158cfbdbe79c03715
Stop using deprecated libvirt_type setting.

Nova's libvirt driver now wants virt_type in the libvirt section.

I've made [libvirt] always be present because our current structure
cannot tell what to do when there are multiple libvirt options (which
my next patch adds). Refactoring of the heat metadata would permit
that - but that should be a separate pass.

Change-Id: Ie9e2a69c3fd51a8a17b44853b2608d95628aab2d
Merge "Restart libvirt-bin when reconfiguring."
Merge "Stop using deprecated libvirt_type setting."