Implementing net config subsystem and revising its interfaces.

Added a few basic configs for device, host and links.

Added initial REST API.

Added CLI.

Tests remain to be added.

Change-Id: Ic7bba4b5ad7d553c51d69f6459b3bff146970323
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/config/basics/SubjectFactories.java b/incubator/api/src/main/java/org/onosproject/incubator/net/config/basics/SubjectFactories.java
new file mode 100644
index 0000000..257bd27
--- /dev/null
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/config/basics/SubjectFactories.java
@@ -0,0 +1,72 @@
+/*
+ * 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.incubator.net.config.basics;
+
+import org.onosproject.core.ApplicationId;
+import org.onosproject.incubator.net.config.SubjectFactory;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.HostId;
+import org.onosproject.net.LinkKey;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+/**
+ * Set of subject factories for potential configuration subjects.
+ */
+public final class SubjectFactories {
+
+    // Construction forbidden
+    private SubjectFactories() {
+    }
+
+    public static final SubjectFactory<ApplicationId> APP_SUBJECT_FACTORY =
+            new SubjectFactory<ApplicationId>(ApplicationId.class, "apps") {
+                @Override
+                public ApplicationId createSubject(String key) {
+                    // FIXME: figure out how to safely create sanctioned app ids
+                    return null;
+                }
+            };
+
+    public static final SubjectFactory<DeviceId> DEVICE_SUBJECT_FACTORY =
+            new SubjectFactory<DeviceId>(DeviceId.class, "devices") {
+                @Override
+                public DeviceId createSubject(String key) {
+                    return DeviceId.deviceId(key);
+                }
+            };
+
+    public static final SubjectFactory<HostId> HOST_SUBJECT_FACTORY =
+            new SubjectFactory<HostId>(HostId.class, "hosts") {
+                @Override
+                public HostId createSubject(String key) {
+                    return HostId.hostId(key);
+                }
+            };
+
+    public static final SubjectFactory<LinkKey> LINK_SUBJECT_FACTORY =
+            new SubjectFactory<LinkKey>(LinkKey.class, "links") {
+                @Override
+                public LinkKey createSubject(String key) {
+                    String[] cps = key.split("-");
+                    checkArgument(cps.length == 2, "Incorrect link key format: %s", key);
+                    return LinkKey.linkKey(ConnectPoint.deviceConnectPoint(cps[0]),
+                                           ConnectPoint.deviceConnectPoint(cps[1]));
+                }
+            };
+
+}