Create a nomulus "curl" command

Create a command to send arbitrary, authenticated HTTP requests to the backend
and remove the existing commands that are basically just wrappers around this.

Tested:
  In addition to the unit tests, verified both get and post requests against
  alpha.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=207756509

java/google/registry/tools/CurlCommand.java

@@ -0,0 +1,89 @@
+// Copyright 2018 The Nomulus Authors. All Rights Reserved.
+//
+// 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 google.registry.tools;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.beust.jcommander.Parameter;
+import com.beust.jcommander.Parameters;
+import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.net.MediaType;
+import java.util.List;
+
+@Parameters(separators = " =", commandDescription = "Send an HTTP command to the nomulus server.")
+class CurlCommand implements ServerSideCommand {
+  private Connection connection;
+
+  // HTTP Methods that are acceptable for use as values for --method.
+  public enum Method {
+    GET,
+    POST
+  }
+
+  @Parameter(
+      names = {"-X", "--request"},
+      description = "HTTP method.  Must be either \"GET\" or \"POST\".")
+  private Method method;
+
+  @Parameter(
+      names = {"-u", "--path"},
+      description =
+          "URL path to send the request to. (e.g. \"/_dr/foo?parm=val\").  Be careful "
+              + "with the shell quoting.",
+      required = true)
+  private String path;
+
+  @Parameter(
+      names = {"-t", "--content-type"},
+      description =
+          "Media type of the request body (for a POST request.  Must be combined with --body)")
+  private MediaType mimeType = MediaType.PLAIN_TEXT_UTF_8;
+
+  // TODO(b/112314048): Make this data flag friendlier (support escaping, convert to query args for
+  // GET...)
+  @Parameter(
+      names = {"-d", "--data"},
+      description =
+          "Body for a post request.  If specified, a POST request is sent.  If "
+              + "absent, a GET request is sent.")
+  private List<String> data;
+
+  @Override
+  public void setConnection(Connection connection) {
+    this.connection = connection;
+  }
+
+  @Override
+  public void run() throws Exception {
+    if (method == null) {
+      method = (data == null) ? Method.GET : Method.POST;
+    } else if (method == Method.POST && data == null) {
+      data = ImmutableList.of("");
+    } else if (method == Method.GET && data != null) {
+      throw new IllegalArgumentException("You may not specify a body for a get method.");
+    }
+
+    // TODO(b/112315418): Make it possible to address any backend.
+    String response =
+        (method == Method.GET)
+            ? connection.sendGetRequest(path, ImmutableMap.<String, String>of())
+            : connection.send(
+                path, ImmutableMap.<String, String>of(), mimeType,
+                Joiner.on("&").join(data).getBytes(UTF_8));
+    System.out.println(response);
+  }
+}