Don't require secondary index when running daemon in slave mode

Add a dummy index implementation and install it when the daemon is
started in slave mode.

Make the reindex program exit with an error if run on a server that
is configured to run in slave mode.

Disable the query ssh command when in slave mode.

Change-Id: Ia323d7dfc3b8f333857ba310072e41943878c11b

gerrit-server/src/main/java/com/google/gerrit/server/index/DummyIndexModule.java

@@ -0,0 +1,26 @@
+// Copyright (C) 2014 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.index;
+
+import com.google.inject.AbstractModule;
+
+public class DummyIndexModule extends AbstractModule {
+
+  @Override
+  protected void configure() {
+    install(new IndexModule(1));
+    bind(ChangeIndex.class).toInstance(new DummyIndex());
+  }
+}