VLANBridge model and parser

VLAN Bridge model contains classes of CIM we didn't have in our router.model bundle.

- VlanBridge is child of the SystemSpecificCollection class. It's related to System with the HostedCollection association.
- ElementName and Description are attributes from the super class of VlanBridge.
- Networkports have been changed to String, since the NetworkPorts was not a direct relation to an object from the model.