ONOS-3460 - Link provider that enforces strict configuration

This provider uses the "links" configuration of the network
config and only allows discovery of links that are in
the config.

Refactoring will be done in a subsequent patch set - the DiscoveryContext and
LinkDiscovery classes are duplicates, they need to be refactored so the
LLDP provider and the Network Config provider can share them.

Change-Id: I4de12fc1c4ffa05e3cac7767b8a31f48ba379f6c
diff --git a/providers/pom.xml b/providers/pom.xml
index f72090b..08364bc 100644
--- a/providers/pom.xml
+++ b/providers/pom.xml
@@ -43,6 +43,7 @@
         <module>bgp</module>
         <module>snmp</module>
         <module>rest</module>
+        <module>netcfglinks</module>
     </modules>
 
     <dependencies>