Add cli for floating ips

Implements a simple cli for managing floating ips. Commands include:

        add-floating-ip Add a floating IP address to a server.
        floating-ip-create Allocate a floating IP to the current tenant.
        floating-ip-delete De-allocate a floating IP from the current tenant.
        floating-ip-list List allocated floating IPs for the current tenant.
        remove-floating-ip Remove a floating IP address from a server.