Install SNAT rules for ipv4 only

Change-Id: I37bd770aa0d54a985ac2bec708c571785084e0ec
Closes-Bug: #1309195
NEC plugin: Bump L3RPC callback version to 1.1

update_floatingip_statuses RPC call implemented in Icehouse expects
RPC version 1.1 and RPC version of L3RpcCallback of other plugins
was bumped to 1.1, but the version of L3RpcCallback in NEC plugin
was not bumped to 1.1 yet.

Change-Id: I0073a3de9ea0cd59d43c821f9bdaea89bd125a65
Closes-Bug: #1323769
Merge "Install SNAT rules for ipv4 only"
Merge "NEC plugin: Bump L3RPC callback version to 1.1"