A couple small things

* Air alarms play a sound when there is either an atmos alarm or a fire alarm in the area. I tried pretty hard to find something that sounded alarm-y without overdoing it. Hopefully this fits the bill.
* Extended the cargo shuttle conveyor belt by one tile. It looks a bit nicer this way.

![screenshot 2014-06-27 23 21 06](https://cloud.githubusercontent.com/assets/242428/3419747/419edffc-fe78-11e3-89be-be7df851b9cd.png)