Read locale from users's preferred language. Do not authenticate from http_header.
Added language and mailing list address columns to lists and users.
Fixed a bug.
Added my_error_messages_for.
Set locale in application_controller. default_url_options is used only when locale is specified in params.
Can edit list's default_language, mailing list address, and color.
Fixed bug of double rendering.
Use lists' default_language as default.
Added validation and scope for mailing_list_address.
Modified message a bit.
Implemented weekly/daily emails for lists with mailing_list_address.