engine: Log mass network operations

Added logging of mass operations of networking commands so that each
network change that causes update of the network on multiple hosts would
output a log similar to:
(7/11): Applying changes for network red on host vds1.

Both start and end (successful or failed) are logged.

Change-Id: Ie86bd5368052b4ed3bd18cff567c39daef911b31
Bug-Url: https://bugzilla.redhat.com/1055161
Signed-off-by: Mike Kolesnik <mkolesni@redhat.com>