Added one more Component Config REST API; for specified component and variable.

Change-Id: I810aa90636c55c8b05c146780ad28c307cefff33
(cherry picked from commit f31ac6ff9f72d040b2da80b6ee5c630ccf9dcc55)
diff --git a/core/api/src/main/java/org/onosproject/cfg/ComponentConfigService.java b/core/api/src/main/java/org/onosproject/cfg/ComponentConfigService.java
index d93cd91..b167297 100644
--- a/core/api/src/main/java/org/onosproject/cfg/ComponentConfigService.java
+++ b/core/api/src/main/java/org/onosproject/cfg/ComponentConfigService.java
@@ -81,5 +81,14 @@
      */
     void unsetProperty(String componentName, String name);
 
+    /**
+     * Returns configuration property of the named components.
+     *
+     * @param componentName component name
+     * @param attribute component attribute
+     * @return configuration property
+     */
+    ConfigProperty getProperty(String componentName, String attribute);
+
 }