network panel freeze break request

[Matthias Clasen <matthias clasen gmail com>]

Here is another networking feature to make the networking situation in
3.0 palatable: implement the device on/off for wired devices (it is
already implemented for wireless, vpn, etc). This matches the network
menu in the shell, which also has an on/off switch for wired.

https://bugzilla.gnome.org/show_bug.cgi?id=645699

While working on this, I noticed that some code in the network panel
is leaking memory, so I'd like to commit that leak fix as well:

https://bugzilla.gnome.org/show_bug.cgi?id=645698