Squashed commit of the following:

commit 82f5d09d389c1de2baa446f6e4c96993e487fd89
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Fri Apr 25 11:41:00 2014 +0900

    add .gitignore

commit 346a0492ade653a42dbb5d071de58491b4547c28
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Fri Apr 25 11:40:19 2014 +0900

    rename directory

commit 4b64b04f899393a678beed4a2a732f92748df123
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Fri Apr 25 10:50:47 2014 +0900

    edit README.md

commit bb5c1042c2c74232199e6e3d6ea984eb5744ae61
Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>
Date:   Fri Apr 25 10:48:44 2014 +0900

    create a sub directory to treat some projects in this git repository