Export list of users and rooms. Take config file as arg. Move errors log.

Updated to:
- export a list of all rooms and a list of all users. Since Campfire doesn't provide a way to fetch all the users in an account, we generate the list based off of which user ids have sent messages.
- take the config file as a command line argument (optional)
- let the user specify the destination of the export (optional) via export_basedir value in the config file