Include codemirror 3.13

Download and package codemirror 3.13 for inclusion in the UI.
This may eventually replace the current side-by-side viewer,
as well as offer rich online editing to make small fixes to
existing changes.

Change-Id: I483fb46d9e18164d189826eca5cb96f9a1471c7e

gerrit-gwtui/src/main/java/net/codemirror/CodeMirror.gwt.xml

@@ -0,0 +1,20 @@
+<!--
+ 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.
+-->
+<module>
+  <inherits name='com.google.gwt.logging.Logging'/>
+  <inherits name='com.google.gwt.resources.Resources'/>
+  <source path='lib'/>
+</module>