TE Topoplogy subsystem I2RS API changes

This submission contains the following:

1. Major changes in apps/tetopology. The changes are mainly introduced
   to support new searching keys in TE Topology.

2. Add RESTCONF notification support in the TE Provider. i.e., for
   south-bound RESTCONF communication with the domain controller.

Change-Id: I6786959deb66c98626edc65ff52694dcf08981a3
diff --git a/apps/tetopology/api/src/main/java/org/onosproject/tetopology/management/api/TeStatus.java b/apps/tetopology/api/src/main/java/org/onosproject/tetopology/management/api/TeStatus.java
new file mode 100644
index 0000000..356a853
--- /dev/null
+++ b/apps/tetopology/api/src/main/java/org/onosproject/tetopology/management/api/TeStatus.java
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.tetopology.management.api;
+
+/**
+ * Represents ENUM data of teStatus.
+ */
+public enum TeStatus {
+
+    /**
+     * Represents up.
+     */
+    UP(0),
+
+    /**
+     * Represents down.
+     */
+    DOWN(1),
+
+    /**
+     * Represents testing.
+     */
+    TESTING(2),
+
+    /**
+     * Represents preparingMaintenance.
+     */
+    PREPARING_MAINTENANCE(3),
+
+    /**
+     * Represents maintenance.
+     */
+    MAINTENANCE(4),
+
+    /**
+     * Status cannot be determined for some reason.
+     */
+    UNKNOWN(5);
+
+    private int teStatus;
+
+    /**
+     * Creates an instance of teStatus.
+     *
+     * @param value value of teStatus
+     */
+    TeStatus(int value) {
+        teStatus = value;
+    }
+
+    /**
+     * Returns the attribute teStatus.
+     *
+     * @return value of teStatus
+     */
+    public int teStatus() {
+        return teStatus;
+    }
+
+    /**
+     * Returns the object of teAdminStatusEnumForTypeInt.Returns null
+     * when string conversion fails or converted integer value is not
+     * recognized.
+     *
+     * @param value value of teAdminStatusEnumForTypeInt
+     * @return Object of teAdminStatusEnumForTypeInt
+     */
+    public static TeStatus of(int value) {
+        switch (value) {
+            case 0:
+                return TeStatus.UP;
+            case 1:
+                return TeStatus.DOWN;
+            case 2:
+                return TeStatus.TESTING;
+            case 3:
+                return TeStatus.PREPARING_MAINTENANCE;
+            case 4:
+                return TeStatus.MAINTENANCE;
+            case 5:
+                return TeStatus.UNKNOWN;
+            default :
+                return null;
+        }
+    }
+}