adding a multicast service to track multicast information.

This will be used by publishers to advertise multicast information
and by consumers to realise it on the dataplane.

This is currently an app but it may be moved to incubation.

Change-Id: I6e350989207ce2207bf70da22ca15c8237b1d240
diff --git a/apps/pom.xml b/apps/pom.xml
index 611ac0b..c016509 100644
--- a/apps/pom.xml
+++ b/apps/pom.xml
@@ -61,6 +61,7 @@
         <module>mfwd</module>
         <module>igmp</module>
         <module>pim</module>
+        <module>mcast</module>
   </modules>
 
     <properties>