Added api.tools.i18n() for internationalization.
Label strings depending on user's locale are referred inside that function.
Changed "Notifications" label to "Updates".
Updated i18n dictionaries.
api.get.unread_notification_emails() still named that way for backward compatibility.
Minor change in README with i18n.
Renamed api.get.unread_notification_emails() to api.get.unread_update_emails().
Missing renaming (for api.get.unread_update_emails()).
Merge pull request #40 from g8g3/i18n

Added api.tools.i18n() for internationalization.