Solve OPENNAAS-1108.

The error was in org.opennaas.extensions.router.capability.vrrp.VRRPCapability.java

updateVRRPVirtualIPAddress method crafted a VRRPProtocolEndpoint param object (not used) but used the original VRRPProtocolEndpoint vrrpProtocolEndpoint to call the action.
Using param to call the action solves the issue by avoiding the error.

http://jira.i2cat.net:8080/browse/OPENNAAS-1108
Slightly improvement of UpdateVRRPVirtualIPAddressAction documentation.
Merge pull request #654 from isartcanyameres/fix/opennaas-1108

Fix/opennaas 1108