Add initial support of i18n.

Currently only 2 messages are translated.
You have to run following command before run:

./manage.py compilemessages
Add initial support of i18n for JavaScript code
Add *.po files to source package
Add make rules to build & install *.mo files
Extract all messages in library.js, maybe
Update meta data in *.po files
Translate all menu items & titles
Translate all messages in "Server Status" page
Translate all messages in base.html & base_ajax.html
Add missing "trans"
Translate all messages in triggers_ajax.html
Translate all messages in events_ajax.html
Translate all messages in latest_ajax.html
Translate all messages in overview_*_ajax.html
Translate messages in dashboard_ajax.html.

Now all messages have been translated, maybe
Fix a message.

Server Status ->
Servers
Merge pull request #62 from project-hatohol/issue10

I merge Issue10.

Thanks ashie-san.