Bugfix/s3conf test redirect

After executing "make" at client_test/python/ceph_tests,
s3-tests/s3test.conf is empty and all tests fail on GNU/Linux(Ubuntu 12.10).

This PR intends to redirect command output to config file without make it background.

Memo:

Behaiviour of "&>" seems to be dependent on shells.
On Ubuntu Linux 12.10 ...

bash: output is redirected

```
    $ bash -c 'echo hoge &> out.txt'
    $ cat out.txt
    hoge
```

zsh: output is redirected

```
    $ rm out.txt
    $ zsh -c 'echo hoge &> out.txt'
    $ cat out.txt
    hoge
```

sh: output is shown in stdout and out.txt remains empty
```
    $ rm out.txt
    $ sh -c 'echo hoge &> out.txt'
    hoge
    $ cat out.txt
```