Revert "Modify Rakefile to enable CI testing."

When former change was done,
`docker restart` command seems not to be required.

In fact, it is. So, reverting the previous commit.

This reverts commit 247986894dc68484a1bb61bdbf0f9a297b92fa40.
Enable kazu634 to execute `iptables-restore` command while CI testing.

Inside Docker container, iptables configuration cannot be applied.

In order to workaround this problem,
the solution is:

  Execute the `iptables-restore` command when logged in as kazu634,
  without asking password.

By enabling kazu634 to execute `iptables-restore` command without asking password,
add entry to /etc/sudoers.d/kazu634.

see also:

- [sshでログインしたときにコマンドを実行する方法](http://kaworu.jpn.org/kaworu/2007-10-19-1.php)
- [特定のコマンドをパスワードなしでsudo する設定 - Slow Dance](http://d.hatena.ne.jp/LukeSilvia/20080716/p1)

This commit fixes #261.
Merge branch 'id/261' into dev