Added i18n mechanism and locale file of Japanese.

You can change the value of "title", "text" or "name" property by chrome i18n message catalog.

ex)
title:
'About App Inspector for Sencha'
to
'App Inspector for Sencha について'

It allows the message key which contains space value. If doesn't exist a message in the catalog, use it just as it is.

![i18n](https://f.cloud.github.com/assets/321647/2447730/2d30f568-ae9c-11e3-9993-1e648831797f.png)