Issue#90

You can remove one loop here by using the include? query

```ruby
all_floating_ips.each do |floating_ip|
  log_attach = floating_ip.instance_id ? "attached to #{floating_ip.instance_id}" : 'not attached'
  @logger.debug " -> #{floating_ip.ip} #{log_attach}" if config.floating_ip_pool.include? floating_ip.pool
  return floating_ip.ip if (config.floating_ip_pool.include? floating_ip.pool) && floating_ip.instance_id.nil?
end unless config.floating_ip_pool_always_allocate
```