Merge pull request #48 from square/alok/readme

Add license to readme

README.md

@@ -116,3 +116,20 @@ If you need ideas on how to contribute, we would enjoy a 3rd backend (Bitcoin-co
 each block by streaming the entire blockchain) as well as additional wallet types (e.g. multisig non-segwit).
 
 Additional unittests and improvements to comments/docs are also always welcome.
+
+License
+=======
+
+    Copyright 2018 Square, 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.