Update supplypacks.dm

Orderable encryption keys.  There are some special headset keys like genetics and robotics that I didn't include.  They can be added later if this actually works.  Also, roboticists don't actually use the robotics encryption key, which lets them listen in on engineering and isn't necessary, so we wouldn't add that anyway.  

I -think- I did the access requirements right, but I'm not positive.  Prices may need tweaking?