[Usability] Burn:// and computer://

[Tom Conneely <tom conneely17 ntlworld com>]

I was thinking about bug 139831 and how the reporter had missed out 
burn:/// as a location. This gave me the idea that it would be nice if 
nautilus could give some indication of whether a CD drive i capable of 
witing (i.e an icon). Then when a blank CD was present in the drive 
allow files to be saved to this drive, essentially making it a device 
specific burn:///.

Would it be a good idea to allow files to be saved here when no CD was 
mounted also, and only block the burn behaviour when a read-only CD was 
in the drive?