webadmin: Save network configuration by default

The default used to be to not persist the network configuration, but a
user complained that his configuration unexpectedly got wiped. Now the
default is to persist the configuration.

Change-Id: Ie855130f05291e33df1609878c76e5023527b27c
Bug-Url: https://bugzilla.redhat.com/1079691
Signed-off-by: Lior Vernia <lvernia@redhat.com>