webadmin: Create default profile when changing to VM network

When a network is switched from VM to non-VM, its associated profiles
are removed. When switching from non-VM to VM, a default profile is
now created again in the GUI.

Change-Id: Ia6764a5d99a9471e6ae07f31ab8552d41b1c28f6
Bug-Url: https://bugzilla.redhat.com/1007279
Signed-off-by: Lior Vernia <lvernia@redhat.com>