CLOUDSTACK-5428: support NetScaler to be configured exclusively for GSLB
service and not used for LB

Fix adds a boolean flag to addNetscalerLoadBalancer api, which
will mark added NetScaler for exclusive GSLB service. A netscaler marked
as exclusive gslb service provider is not picked for any guest network's
lb provider.
CLOUDSTACK-5412: UI > Add Secondary Storage > provider dropdown > change option "SMB/cifs" to "SMB/CIFS".
CLOUDSTACK-5297: Fix ACL rules on VPN for VPC

Insert a new iptables chain for FORWARD chain, in order to let following ACL
rules being executed as well.
add Apache Licensed