Squashed commit of the following:

commit ad586d41a83aa5c26f9625f4be22330722308820
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Wed Oct 8 11:40:55 2014 +0900

    Add README.md

commit 6efcb2853311cddb33be62afdf2e868aaf155e5e
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Wed Oct 8 11:35:40 2014 +0900

    Add documents

commit fc7dfa933613fd87009ceca17df858c2490560af
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Tue Oct 7 14:47:12 2014 +0900

    Add a benchmark result on master:r3.large, slavex2:r3.8xlarge