add the devices section to the domain specification

[calavera]

Hey Mitchell, I just added the devices section to the spec, there are still some missing sections under devices but it's mostly complete.

I'm getting a convention that I think we should follow, any primary element that requires an attribute gets it from the constructor, for instance the disk specification takes the type as mandatory parameter:

<disk type='file'>...</disk>

Libvirt::Spec::Disk.new('file')

I've also seen that we don't have any test on the spec, I'll try to add some basic ones this weekend.

[mitchellh]

David, I'm currently out of town so I'll look at this when I get a chance :) It looks good its just a lot to grasp and such.

As for the tests, yes some tests would be good. I initially didn't do any testing since most of the tests would be trivial and not very helpful. "assert XML has memory in the output" and so on :P But I think testing to make sure the more complex logic that is visible works.

[calavera]

No problem, so I have time to add the tests :) Enjoy your weekend

[mitchellh]

Back from the weekend! Looks really awesome! Amazing. I'm working on getting this in now.

[mitchellh]

I do notice a couple things I'm going to switch around in the coming days but it mostly looks good. Great job.