Add ACP module and interface

This depends on PR #3 being merged first.

Note: If the acp module looks like a lot, it's not really, it's just that I commented every line :wink: 
For the next PR. We will need to use cookies if we want Guests to hide the announcement and not see it again. The timestamp is used like an ID for this announcement and the cookie. This may also come in handy if we decide to add expiration dates in the future to announcements.