Description of problem:
In an openstack environment with multiple external networks, the operator can specify a default network ("openstack network create --default ..."), with the expectation that users will allocate addresses from this network if they don't make an explicit choice to use another one.
Horizon presents floating ip pools in unsorted order, which means that when allocating an ip address, the pool selected by default will often not be the "default" pool.
Horizon should have the default pool selected by default.
I've submitted https://review.openstack.org/#/c/623582/ as one way of implementing this suggestion.