Reserve an ip without restarting galaxy-ipam

[chenchun]

Currently, if we want to reserve an ip, we need to update the floatingip-config configmap. But this is not possible if floatingip-config configmap is synced by a program automatically which may override the update.
We can also create a floatingip crd and restart galaxy-ipam to reserve an ip. To avoid restarting, we can watch floatingip objects and thus reserve the ip.