Ensure floating IP is used as public address for openstack

Fixes https://bugs.launchpad.net/juju-core/+bug/1348287

If a floating IP address is requested for an Openstack instance, we know that will be the public address. That one should be reported as such instead of trying to guess. Often the guesses can be wrong.


space after //
s/te/the/

I think it'd be easier to grok if you just wrote:
    // floatingIP is non-nil iff use-floating-ip is true.