support networking settings

[Jacob Peddicord]

This task is for making a limited amount of settings for manual networking available in the UI for networking, networking/lo, networking/etc1, etc.

I'm still uncertain about the need of this:
* on the desktop, a user should be using network-manager to configure their network
* on the server, assuming a console couterpart to jobs-admin, a system administrator is likely able to manually configure their network more quickly than through SLS.

I wouldn't object to a setting that prompts the user to open an external network-manager utility. However, I'm not sure we should be suggesting users manually configure their network on a desktop either: it will create confusion when suddenly network-manager reports that "networking is disabled."

On top of this, SLS is designed for one set of settings per *service*, not per service *instance*. Significant changes would need to be made here, though if there's good reasoning behind this I'm willing to do it.

Opinions and comments for or against are welcome. I'll look into more of the technical details of this, but I'm not sure to what extent this could be done before feature freeze.

[Jacob Peddicord (jpeddicord)]

Things are at a point where basic network settings can be configured: hostname, ip/subnet/gateway per interface. More work to be done, but it seems to be functional now.