Add the list of contributors

Add the list of contributors in a separate file and add links
to the LICENSE and CONTRIBUTORS files.

Fixes #28

CONTRIBUTORS

@@ -0,0 +1,11 @@
+# The list of people who have contributed code to the cmux repository.
+#
+# Auto-generated with:
+# git log --oneline --pretty=format:'%an <%aE>' | sort -u
+#
+Dmitri Shuralyov <shurcooL@gmail.com>
+Ethan Mosbaugh <emosbaugh@gmail.com>
+Soheil Hassas Yeganeh <soheil.h.y@gmail.com>
+Soheil Hassas Yeganeh <soheil@cs.toronto.edu>
+Tamir Duberstein <tamir@cockroachlabs.com>
+Tamir Duberstein <tamird@gmail.com>

README.md

@@ -74,3 +74,10 @@ gRPC server please match with writers:
 ```go
 grpcl := m.MatchWithWriters(cmux.HTTP2MatchHeaderFieldSendSettings("content-type", "application/grpc"))
 ```
+
+# Copyright and License
+Copyright 2016 The CMux Authors. All rights reserved.
+
+See [CONTRIBUTORS](https://github.com/soheilhy/cmux/blob/master/CONTRIBUTORS)
+for the CMux Authors. Code is released under
+[the Apache 2 license](https://github.com/soheilhy/cmux/blob/master/LICENSE).