Missing "Image: Software:" for some platforms

[Stafford A. Rau]

I'd like to be able to extract the running IOS version for all of our
Cisco platforms from the rancid configs, but we're missing the '!Image:
Software:' lines from some of them.

Specifically, I don't see it for our 7609s, 6509s (running native IOS),
and less importantly, our PIXes.

I'd be quite happy to supply any command output from those devices to
facilitate this feature request.

We're running rancid version 2.3.1.

Thanks,
--Stafford