Disassociate a floating IP from server

        .. versionadded:: 2016.3.0

def floating_ip_disassociate(self, server_name, floating_ip):
        '''
        Disassociate a floating IP from server

        .. versionadded:: 2016.3.0
        '''
        nt_ks = self.compute_conn
        server_ = self.server_by_name(server_name)
        server = nt_ks.servers.get(server_.__dict__['id'])
        server.remove_floating_ip(floating_ip)
        return self.floating_ip_list()[floating_ip]