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.

This update currently affects:
* Request console announcements
* Priority announcements from message consoles
* All announcements which previously used captain_announce()
* Code Green/Blue/Red/Delta changes
* ERT request announcements

All affected automated announcements, such as shuttle messages, should behave exactly the same as before save that some will be saved as newsfeeds.

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