Improve naming of 'release' function in IPAM API

plugin/ipam/driver.go

@@ -92,7 +92,7 @@ func (i *ipam) RequestAddress(poolID string, address net.IP, options map[string]
 
 func (i *ipam) ReleaseAddress(poolID string, address net.IP) error {
 	Log.Debugln("ReleaseAddress", poolID, address)
-	return i.weave.ReleaseIP(address.String())
+	return i.weave.ReleaseIPsFor(address.String())
 }
 
 // Functions required by ipamapi "contract" but not actually used.