webadmin: Don't add VNICs to a VM by default

VNICs used to be added to VMs created from VNIC-less templates by
default, to accommodate assigning some sort of network connection to a
VM when creating it. This is no longer needed, as VNICs can now be
added and removed by the user in the same dialog.

Change-Id: I2d00fd6a4fb280d9604bc1ae586fcc588d4a7196
Bug-Url: https://bugzilla.redhat.com/1003779
Bug-Url: https://bugzilla.redhat.com/1009298
Bug-Url: https://bugzilla.redhat.com/1010856
Signed-off-by: Lior Vernia <lvernia@redhat.com>