Add top level /config REST API

/config/server/ part is hard coded for now, but we may add more
config specific resource names later.

/config/server/capabilities retrieves the known server wide
capabilities list. The list has to be loaded dynamically from
the server to permit plugins to declare their own capabilities.

Change-Id: I83692bd021925d37659bfbc88b3e3b67b92c18c1

gerrit-server/src/test/java/com/google/gerrit/server/config/ListCapabilitiesTest.java

@@ -0,0 +1,39 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.config;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gerrit.common.data.GlobalCapability;
+import com.google.gerrit.server.config.ListCapabilities.CapabilityInfo;
+
+import org.junit.Test;
+
+import java.util.Map;
+
+public class ListCapabilitiesTest {
+  @Test
+  public void testList() throws Exception {
+    Map<String, CapabilityInfo> m =
+        new ListCapabilities().apply(new ConfigResource());
+    for (String id : GlobalCapability.getAllNames()) {
+      assertTrue("contains " + id, m.containsKey(id));
+      assertEquals(id, m.get(id).id);
+      assertNotNull(id + " has name", m.get(id).name);
+    }
+  }
+}