[ONOS-4438] Add codecs for mastership REST API

Add codecs for RoleInfo, MastershipTerm and MastershipRole.

Change-Id: I1135c7fc0ed591446d6268229b54fda70391fdb9
diff --git a/core/common/src/test/resources/org/onosproject/codec/impl/RoleInfo.json b/core/common/src/test/resources/org/onosproject/codec/impl/RoleInfo.json
new file mode 100644
index 0000000..a4b5b40
--- /dev/null
+++ b/core/common/src/test/resources/org/onosproject/codec/impl/RoleInfo.json
@@ -0,0 +1,8 @@
+{
+  "master": "1",
+  "backups": [
+    "2",
+    "3",
+    "4"
+  ]
+}
\ No newline at end of file