Update \Gasoline\Message::render

* Add arguments $before and $after to wrap the messages in tags other
than the ones specified in config/message.php
* Change name of config options for \Gasoline\Message
Update \Gasoline\Message::set()

Add logic to handle passing $message as type \Validation_Error to
Message::set()
Add \Gasoline\Message::validation_errors()

Allows for setting the validation errors to the active message-container
Update \Gasoline\Message::set() with some speed enhancements