In preparation for dynamic clustering support:
- Added Cluster metadata service and metadata store interfaces
- Added a static cluster metadata store implementation that is backed by a local file.
- Consolidated the existing cluster.json and tablets.json metadata files into a single cluster.json file that has all the cluster related metadata.
- Removed dependency on ONOS_NIC env variable.

Change-Id: Ia0a8bb69740caecdcdde71a9408be37c56ae2504
diff --git a/core/api/src/main/java/org/onosproject/cluster/ClusterMetadataStore.java b/core/api/src/main/java/org/onosproject/cluster/ClusterMetadataStore.java
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+++ b/core/api/src/main/java/org/onosproject/cluster/ClusterMetadataStore.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2015 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.cluster;
+
+import java.util.Collection;
+
+import org.onosproject.store.Store;
+import org.onosproject.store.service.Versioned;
+
+/**
+ * Manages persistence of cluster metadata; not intended for direct use.
+ */
+public interface ClusterMetadataStore extends Store<ClusterMetadataEvent, ClusterMetadataStoreDelegate> {
+
+    /**
+     * Returns the cluster metadata.
+     * <p>
+     * The returned metadata is versioned to aid determining if a metadata instance is more recent than another.
+     * @return cluster metadata
+     */
+    Versioned<ClusterMetadata> getClusterMetadata();
+
+    /**
+     * Updates the cluster metadata.
+     * @param metadata new metadata value
+     */
+    void setClusterMetadata(ClusterMetadata metadata);
+
+    // TODO: The below methods should move to a separate store interface that is responsible for
+    // tracking cluster partition operational state.
+
+    /**
+     * Sets a controller node as an active member of a partition.
+     * <p>
+     * Active members are those replicas that are up to speed with the rest of the system and are
+     * usually capable of participating in the replica state management activities in accordance with
+     * the data consistency and replication protocol in use.
+     * @param partitionId partition identifier
+     * @param nodeId id of controller node
+     */
+    void setActiveReplica(String partitionId, NodeId nodeId);
+
+    /**
+     * Removes a controller node as an active member for a partition.
+     * <p>
+     * Active members are those replicas that are up to speed with the rest of the system and are
+     * usually capable of participating in the replica state management activities in accordance with
+     * the data consistency and replication protocol in use.
+     * @param partitionId partition identifier
+     * @param nodeId id of controller node
+     */
+    void unsetActiveReplica(String partitionId, NodeId nodeId);
+
+    /**
+     * Returns the collection of controller nodes that are the active replicas for a partition.
+     * <p>
+     * Active members are those replicas that are up to speed with the rest of the system and are
+     * usually capable of participating in the replica state management activities in accordance with
+     * the data consistency and replication protocol in use.
+     * @param partitionId partition identifier
+     * @return identifiers of controller nodes that are the active replicas
+     */
+    Collection<NodeId> getActiveReplicas(String partitionId);
+}
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