[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/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java b/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java
index bd89102..81fb220 100644
--- a/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java
+++ b/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java
@@ -468,6 +468,17 @@
     }
 
     /**
+     * Returns the MPLS-ECMP configuration.
+     *
+     * @return MPLS-ECMP value
+     */
+    public boolean getMplsEcmp() {
+        SegmentRoutingAppConfig segmentRoutingAppConfig = cfgService
+                .getConfig(this.appId, SegmentRoutingAppConfig.class);
+        return segmentRoutingAppConfig != null && segmentRoutingAppConfig.mplsEcmp();
+    }
+
+    /**
      * Returns the tunnel object with the tunnel ID.
      *
      * @param tunnelId Tunnel ID