Implement new /changes/{id}/action style REST API

All existing JSON APIs are converted to this new style.

/changes/{id} parses the id field from a JSON response from a prior
response and uses that to uniquely identify a change and verify the
caller can see it. If the user requests only /changes/{id}/ then the
data is returned as a single JSON object.

This commit also gives full remote control of plugins using the
/plugins/ namespace:

  PUT /plugins/{name}    (JAR as request body)
  POST /plugins/{name}   (JSON object {url:"https://..."})
  DELETE /plugins/{name}
  GET /plugins/{name}/gerrit~status
  POST /plugins/{name}/gerrit~reload
  POST /plugins/{name}/gerrit~enable
  POST /plugins/{name}/gerrit~disable

The commit provides some project admin commands:

  GET /projects/{name}/description
  PUT /projects/{name}/description

  GET /projects/{name}/parent
  PUT /projects/{name}/parent

Project dashboards have moved:

  GET /projects/{name}/dashboards
  GET /projects/{name}/dashboards/{id}
  GET /projects/{name}/dashboards/default

To access project names containing /, the name must be encoded with
URL encoding, translating / to %2F.

Change-Id: I6a38902ee473003ec637758b7c911f926a2e948a

gerrit-server/src/main/java/com/google/gerrit/server/project/GetDashboard.java

@@ -0,0 +1,33 @@
+// Copyright (C) 2012 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.project;
+
+import static com.google.gerrit.server.git.GitRepositoryManager.REFS_DASHBOARDS;
+
+import com.google.gerrit.extensions.restapi.RestReadView;
+
+import java.io.UnsupportedEncodingException;
+
+class GetDashboard implements RestReadView<DashboardResource> {
+  @Override
+  public Object apply(DashboardResource resource)
+      throws UnsupportedEncodingException {
+    return DashboardsCollection.parse(
+        resource.getControl().getProject(),
+        resource.getRefName().substring(REFS_DASHBOARDS.length()),
+        resource.getPathName(),
+        resource.getConfig());
+  }
+}