engine: Audit log warning about display network connectivity change. (CollectVdsNetworkDataVDSCommand)

The warning that let the user to understand that the changes in
display network will be applied not instantly, but on the next
VM restart. The change is done in CollectVdsNetworkDataVDSCommand.

Change-Id: I9949fc6ed52871ccfb1a15397e2cc722ad231b8f
Bug-Url: https://bugzilla.redhat.com/1078836
Signed-off-by: Yevgeny Zaspitsky <yzaspits@redhat.com>