engine: SetupNetworks rollback error message

Adding a message for a failed setup networks command
which was invoked with 'check connectivity'.

Change-Id: I80a0d9ad2be6094dd8c4fa6b0fcbf533865b5082
Bug-Url: https://bugzilla.redhat.com/1072794
Signed-off-by: Moti Asayag <masayag@redhat.com>