Fix: MetaStation Compiles Again

Updated MetaStation v27G-II.dmm to MetaStation v27G-III.dmm
- Replaced Janitor's Wagon with new Janitor's Cart
- Replaced all station bounced radios with the 'off' variant
- Updated holodeck to be as current main /tg/station
- Fixed broken reference to a data disk on display.
- Compiles again.

Please note that this was a minor bugfix to get the map working again, as requested. There is also a much larger overhaul of the map in progress, with many more improvements. Watch this space. 

A note to Carn: 
Don't close this because you don't like it being in the repo, this fix was requested because someone wanted to try running the map again. This is easy and quick to implement, and it all works, just needs green-lighting on here. We'll get the map out of the repo soon enough, but for now if it's in there it might as well work.