Added support in the TopologyManager for processing explicitly configured
Topology Elements.

This is needed for the Optical topology use case.

Also, modified TopologyElement.getConfigState() : if there is no
CONFIG_STATE attribute, then return NOT_CONFIGURED as a default value.

Change-Id: I6e1c6899b750094948c106c1a6f981ec73774303
diff --git a/src/main/java/net/onrc/onos/core/topology/TopologyElement.java b/src/main/java/net/onrc/onos/core/topology/TopologyElement.java
index f169456..81ecb1f 100644
--- a/src/main/java/net/onrc/onos/core/topology/TopologyElement.java
+++ b/src/main/java/net/onrc/onos/core/topology/TopologyElement.java
@@ -195,7 +195,8 @@
      */
     @Override
     public ConfigState getConfigState() {
-        return ConfigState.valueOf(getStringAttribute(ELEMENT_CONFIG_STATE));
+        return ConfigState.valueOf(getStringAttribute(ELEMENT_CONFIG_STATE,
+                                                      ConfigState.NOT_CONFIGURED.toString()));
     }
 
     /**
@@ -207,5 +208,4 @@
     public AdminStatus getStatus() {
         return AdminStatus.valueOf(getStringAttribute(ELEMENT_ADMIN_STATUS));
     }
-
 }