Rename L2 load balancer to port load balancer

CLI commands are also renamed to plbs, plb-add and plb-remove

Change-Id: I4c26b390acc5a961594a1dca92a76bee2148c090
diff --git a/apps/segmentrouting/BUCK b/apps/segmentrouting/BUCK
index f56834e..fbe7b812 100644
--- a/apps/segmentrouting/BUCK
+++ b/apps/segmentrouting/BUCK
@@ -12,6 +12,6 @@
     required_apps = [
         'org.onosproject.route-service',
         'org.onosproject.mcast',
-        'org.onosproject.l2lb',
+        'org.onosproject.portloadbalancer',
     ],
 )