engine_page: network is required to register tab

oVirt Engine tab will only show the options for register
once the oVirt Node has the network setup.

Change-Id: Ic2563804673954234f3c29fed80ca54fe195d35a
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1064206
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>