International friendly README

As mentioned in #14 .

I also updated the `lang` attribute in html template because it will cause annoying translating message on Chrome:
![image](https://cloud.githubusercontent.com/assets/2840571/3732039/f9b90dde-16f5-11e4-9b2c-56d4c0f20572.png)

May not be a problem.
But, as a specification of HTML5, to be the `lang="ja"` and if Japanese.

We think in the future, and should be in the configuration options.