CORD-73 Change the way we configure host learning in segment routing

hostLearning config
    - true: enable host learning
    - false or not provided: disable host learning
suppressHost config
    - all connect points listed here will be ignored
    - no effect if hostLearning is false
    - accept all hosts if this config is not provided

Change-Id: Id4a60bd47cac1f226ab8ba5391931ad2fb798529
diff --git a/src/test/resources/sr-app-config-invalid.json b/src/test/resources/sr-app-config-invalid.json
index e2851d5..72def14 100644
--- a/src/test/resources/sr-app-config-invalid.json
+++ b/src/test/resources/sr-app-config-invalid.json
@@ -11,5 +11,6 @@
   "suppressHost" : [
       "of:1/1",
       "wrongPort"
-  ]
+  ],
+  "hostLearning" : false
 }