[CORD-578] MPLS ECMP configurable

Changes:
- Adds MPLS-ECMP option to SR configuration;
- Updates the json examples;
- Implements unit tests to verify the expected behaviors;

Change-Id: I6a7f5d34161be7c85ecb76c9a09288d960aad3cb
diff --git a/src/test/resources/xconnect.json b/src/test/resources/xconnect.json
index ab9cfe6..ebd61b3 100644
--- a/src/test/resources/xconnect.json
+++ b/src/test/resources/xconnect.json
@@ -16,4 +16,4 @@
       "ports": [4, 5]
     }
   ]
-}
\ No newline at end of file
+}