Expose the enableIPv6 setting

Signed-off-by: Aidan Hobson Sayers <aidanhs@cantab.net>

libnetwork/network.go

@@ -62,6 +62,7 @@ type NetworkInfo interface {
 	IpamInfo() ([]*IpamInfo, []*IpamInfo)
 	DriverOptions() map[string]string
 	Scope() string
+	IPv6Enabled() bool
 	Internal() bool
 }
 
@@ -1237,3 +1238,10 @@ func (n *network) Internal() bool {
 
 	return n.internal
 }
+
+func (n *network) IPv6Enabled() bool {
+	n.Lock()
+	defer n.Unlock()
+
+	return n.enableIPv6
+}