Announcement Refactoring

Turns announcements into a datum based system to allow a variety of configurations.
Current configuration options include:
Admin logging
Which sound that should play when announced, if any
If the announcement should be stored as a newscast
A name for the announcer.

Request console/standard announcements currently match priority announcements, but have a smaller style/footprint.
Player announcements now include the assignment and name of the person (or the id rather) who made it.

Have currently only updated the request console and all announcements which previously used captain_announce().
Affected automated announcements, such as shuttle messages, should be exactly the same as before.

As you may note it shouldn't be too difficult to create new announcement styles and I'm considering doing something about most world << calls to achieve consistency if nothing else.

For images and the like, see the discussion thread:
http://baystation12.net/forums/viewtopic.php?f=5&t=11116
Air horn because it was the first attention grabbing sound I came across. Should probably be something else, perhaps even no sound.