Provider network MEF ENNI OVC update

Added stubs for metro ethernet forum ( #MEF ) external network to network interfaces ( #ENNI ) and operator virtual circuits ( #OVC ) management support in #bridge module. This will enable MEF recognized attributes to be configured on ENNI ports in the provider network.

#Ethernet update 22 ...
[commit 6a0b0b485946629eacd3114c481ea711e1ec6aef]