Add LICENSE file. Reviewed in http://codereview.appspot.com/6055051/.

LICENSE

@@ -0,0 +1,23 @@
+ Copyright (C) 2010-2012 Google Inc.
+
+ 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.
+
+Dependent Modules
+=================
+
+This code has the following dependencies
+above and beyond the Python standard library:
+
+uritemplates - Apache License 2.0
+httplib2 - MIT License
+python-gflags - New BSD License