Adopted restart for use with network.service alias link

Adopted restart / reload using NetworkService instead Service, that
has been changed to use network.service alias link installed by the
NetworkManager service file while "systemctl enable".
It obsoletes the use of the NETWORKMANAGER=yes/no sysconfig variable
in /etc/sysconfig/network/config (bnc#764055,bnc#764336,bnc#798348).